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Highly even so in this video, they're going to solve this question symmetric by Nutri.

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OK, so they will basically be a binary tree and we have to return, whether that by Newton's symmetric

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or not.

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OK, so basically the return type is basically a boolean value.

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I have to return.

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True or false?

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True.

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If the given tree is basically symmetric tree, otherwise I have to return false.

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OK, so let us consider an example and let's see what is a symmetric by nutri.

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So let us consider this example.

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So what I will do, I will draw a centerline.

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OK.

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Now, I will compare the values, I will compare the values, so in this case, so I will compare the

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value as well as the structure.

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OK, so I will compare.

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Value and structure, both should be seen on the left and the right hand side of this middle line.

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OK, now values I seem to want to and also distances seem if this distance is this distance is also

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OK.

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So value and distance assim.

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Now let's move ahead.

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Let's compare for to so for and for values the same distances also same BMV.

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Now compare three with three.

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OK, so if the distance is this distance is already ok.

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And again the values are same.

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So basically this tree, this tree is a symmetric tree so I will return.

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True.

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OK, now let us consider this tree.

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So industry.

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First of all, it does draw the line.

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And now let us compare the values and the structure, OK, values our same distances, also same let's

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call it the.

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So in this case, values are simply entry, but the states are different.

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So in this case, let's call it divine.

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And this distance is basically data.

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OK, so this is not a symmetric boundary, OK?

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This is not symmetric.

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So I will return calls for this by nutri.

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OK, so I hope you understood the question.

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Now suppose this is the root node now.

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Root node.

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This is the left subtree.

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Let's call it three one.

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This is the right subtree of the root.

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Let's call it due to OK, Rita.

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Driven driven to do so when this.

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So what is the condition for this tree to be a small victory.

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OK, so there are very small, small conditions.

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So first condition is basically.

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If the values of OK, so basically first condition is Wellinghoff, everyone's ruled is equal to the

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Valley of the Dolls to.

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OK.

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The second condition is basically.

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The events left subtree.

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Should be symmetric with details, right subtree.

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OK, so we can see here I am comparing.

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OK, so this is everyone, let's call it Reto.

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OK, so 41 if I'm calling with the left hand side, so 42, I will call on the right and say, OK,

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so 41, this is left 42.

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This is right.

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OK, so everyone's left should be close to it should be symmetric to deduce.

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Right.

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And a third condition is basically the ones.

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Right.

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Should be symmetric to reduce left.

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OK, so these are the very simple, simple conditions.

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Now, what we can do, we can we can make the help of recursion and we can solve this question with

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the help of these three conditions.

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OK, you can see here so 42 if I'm comparing four.

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So I will call on the right hand side, but 42 to compare for.

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I will call on the left hand side.

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OK, so I hope you understood the question.

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Now let us write the code, OK, remembering these three conditions.

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So basically, they of the function is asymmetric, we have to complete this function, then put as

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basically a tree and the return type is whether they're given trees symmetric or not.

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OK.

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So first of all, the base case.

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So if rotational, then I can say that given today's symmetrical, so I can return to.

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OK, so now let us create a helper function.

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OK, so.

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Let us create a helper function which will do our work so that it will obviously be able I have helper

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function, so it will take two tries to compare.

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OK.

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It will take two raise as input, so the left separates the left and the right tree.

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OK, so this helper function will do our work and what I will do, so let us call this function helper

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function and I will pass the left and the right subtree.

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OK, so what I am doing here is so basically I am creating a helper function.

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OK, and this helper function will take place as input and it will compare these duties.

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OK, so, for example, let us consider this.

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So this helper function will take this tree as input.

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So it is stored in the left variable and this tree will be stored in the right variable.

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OK, so I comparing these two trees.

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Two, three, four, and the right is basically two for three, OK, I am passing the left subtree and

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I am passing the right subtree.

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OK, so now let us complete the court.

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So the court is going to be very, very simple.

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Now, let us take care of a few situations, a few simple, simple cases.

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OK, so case number one.

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So if the left Presnell.

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And the right tree is not.

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OK, so basically the right tree is nocturnal, then they are not symmetric.

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So I can return false.

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Simple.

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Now, similarly.

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So if the left today is not OK, left pre-exist, but right, it does not exist, so right, reasonable

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and left is not null, then also I can return false.

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Simple now, if the values are different, OK, so if the value of lefty.

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It's not a close to the valley of right tree.

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Then in that case, I can also return false.

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Simple.

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OK, so if the levels are Presnell and right, if not, then return false.

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If the left is not all right, then then also return false.

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If their values are different, then also return false.

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They are not symmetric.

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OK, so force structure should be same and the values should also be the same.

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Now, there can be one more condition if the tunnel OK.

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If both left and right, so in that case, I can return to.

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So if left and right is also nil.

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Then I can return true safely.

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OK, so these are very simple, simple conditions now what we have to do.

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So I have to make use of these two conditions, OK?

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I will make use of these two conditions.

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We have already handled this one, OK, if you will see the code, we have already handled the condition.

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Now let us handle these two conditions.

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OK, I have to pass the left.

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And was right, and similarly, if he wins right, then it's left.

126
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OK.

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So the name of the function is helper.

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So, OK, I have to change the name, because you can see left and right have already been used.

129
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OK, so let's name it left three.

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And this is right, three.

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OK, so now that is called helper function, and we will take we will make use of these two conditions.

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OK.

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So.

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If left three.

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So if I'm giving the left three left, then I have to give right three, right.

136
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So these two trees should be symmetric and.

137
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If I'm giving.

138
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The left three right, then I have to pass the left of the right tree.

139
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OK.

140
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So right we left.

141
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Very simple.

142
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OK, so this is basically driven this is basically to do OK, so this is route.

143
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Everyone is this one and two is this one.

144
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OK, so these are very simple, four conditions.

145
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OK, now I'm calling the helper function.

146
00:09:48,330 --> 00:09:49,860
So for the helper function.

147
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If I am passing through, you once left, so Trillanes left, that means decide, OK, three months

148
00:09:57,470 --> 00:10:00,260
left, then I have to pass it right.

149
00:10:00,260 --> 00:10:01,520
So Britos right.

150
00:10:03,520 --> 00:10:09,730
OK, then only they will be at the same distance, so if this distance is deep, then also this distance

151
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will be OK and we are using and OK.

152
00:10:13,450 --> 00:10:16,410
And if I am comparing Even's, right.

153
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So this is the once right, then I have to compare it to the left.

154
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So this is due to the left.

155
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OK, this distance is deep, then only this distance will be OK if everything if this whole tree's symmetric

156
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to this tree we are using the end condition, then only I will return to OK, otherwise I will return

157
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false.

158
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OK, very, very simple.

159
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So what is the complexities or time complexities big often.

160
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And the space complexity is also big, often due to recursion.

161
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OK, so very simple and very logical.

162
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OK.

163
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OK, so now letters are now called.

164
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OK, so we are getting random error at this lane.

165
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Now let's see why.

166
00:11:10,000 --> 00:11:16,210
OK, so obviously we will get rain tomorrow, and I suppose if the left reasonable, if the left Presnell,

167
00:11:16,420 --> 00:11:18,660
then how can you assess the value of nil?

168
00:11:19,060 --> 00:11:23,260
And similarly, if the right reason, then how we can assess the value of nil.

169
00:11:24,790 --> 00:11:26,470
So that's why we are getting there in time.

170
00:11:26,790 --> 00:11:33,640
OK, so to solve this problem, what can I do so I can write this line below this line?

171
00:11:33,710 --> 00:11:38,310
OK, so I will write line number 16 before line number 15.

172
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OK, that will solve our problem.

173
00:11:42,280 --> 00:11:42,970
Now, let's see.

174
00:11:44,790 --> 00:11:53,640
So just remove this line and write this line the last, OK, so I have to write this line after this

175
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line because headline number 15, I am checking if left reasonable and retrieve the boat and then return.

176
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True.

177
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OK, so when we will reach line number 17, I am very sure that left, pre-exist and right also exist.

178
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OK, so now if you will run call.

179
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Our goal will work fine, hopefully.

180
00:12:16,690 --> 00:12:17,920
OK, now let's admit.

181
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OK, so our goal is working for success.

182
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OK, so if you have any doubt, you can ask me.

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Thank you.