pb8

Author: EISAWESOME

pb8/Problem.md

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+> This problem was asked by Google.
+
+A unival tree (which stands for "universal value") is a tree where all nodes under it have the same value.
+Given the root to a binary tree, count the number of unival subtrees.
+For example, the following tree has 5 unival subtrees:
+
+```
+   0
+  / \
+ 1   0
+    / \
+   1   0
+  / \
+ 1   1
+```

pb8/answer.js

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+
+class Node {
+  constructor(val, left=null, right=null) {
+    this.val = val;
+    this.left = left;
+    this.right = right;
+  }
+}
+
+// Same tree as example
+const tree =                        new Node(0,
+
+                          new Node(1),              new  Node(0,
+
+                                            new Node(1,                 // 0
+
+                                        1,              1) ,            new Node(0)));
+
+
+
+const countUnival = (root) => {
+  let nbUnival = 0;
+
+  const processNode = (node, value) => {
+
+    if(node.right || node.left) {
+      if( node.right) {
+        if(node.right.val === value) {
+          if(processNode(node.right, value)){
+            nbUnival++;
+          }
+        } else {
+          return processNode(node.right, value);
+        }
+      }
+
+      if(node.left) {
+        if(node.left.val === value) {
+          if(processNode(node.left, value)) {
+            nbUnival++;
+          }
+        } else {
+          return processNode(node.left, value);
+        }   
+      }
+  
+    } else {
+      nbUnival++;
+      return true;
+    }
+  }
+  processNode(root, root.val);
+  return nbUnival;
+
+}
+console.log(countUnival(tree));