diameter of btree

Author: specialtactics

week2/diameter-of-binary-tree.c

@@ -0,0 +1,48 @@
+// Simple implementation of max from stack
+ #define max(a,b) \
+ ({ __typeof__ (a) _a = (a); \
+ __typeof__ (b) _b = (b); \
+ _a > _b ? _a : _b; })
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ * int val;
+ * struct TreeNode *left;
+ * struct TreeNode *right;
+ * };
+ */
+
+
+int diameterOfBinaryTree(struct TreeNode* root) {
+ // Special cases
+ if (root == NULL || root->left == NULL && root->right == NULL) {
+ return 0;
+ }
+
+ int highestSum = 0;
+ int longestDistance = longest(root, &highestSum) - 1; // Subtract 1 for root
+ 
+ return max(longestDistance, highestSum);
+}
+
+/**
+ * Return longest distance for one node
+ */ 
+int longest(struct TreeNode* node, int* highestSum) {
+ int right = 0, left = 0;
+ 
+ if (node->left != NULL) {
+ left = longest(node->left, highestSum);
+ }
+ if (node->right != NULL) {
+ right = longest(node->right, highestSum);
+ }
+ 
+ // Maintain highest sum
+ if (right + left > (*highestSum)) {
+ *highestSum = right + left;
+ }
+ 
+ return (max(left, right) + 1);
+}