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authorjack <[email protected]>2024-06-14 13:13:15 -0600
committerjack <[email protected]>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /longest_zigzag_bt.c
downloadleetcode-d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa.tar.gz
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+// 1372. Longest ZigZag Path in a Binary Tree
+#include <math.h>
+#include <stdlib.h>
+
+/*
+ * given the 'root' of a binary tree. a zigzag path for a binary tree is defined
+ * as follows
+ * - choose any node in the binary tree and a direction (left or right)
+ * - if the current direction is right, move to the right child of the current
+ * node
+ * - change the direction from right to left or from left to right
+ * - repeat the second nd third steps until you cannot move in the tree
+ * zigzag length is defined as the number of nodes visited - 1. return longest
+ * zigzag
+ */
+
+struct TreeNode {
+ int val;
+ struct TreeNode *left;
+ struct TreeNode *right;
+};
+
+typedef struct {
+ int left;
+ int right;
+} data;
+
+data process(struct TreeNode *root, int *max) {
+ data res;
+ if (!root) {
+ res.left = -1;
+ res.right = -1;
+ return res;
+ }
+ data l_tree = process(root->left, max);
+ data r_tree = process(root->right, max);
+ res.left = 1 + r_tree.right;
+ res.right = 1 + l_tree.left;
+ *max = fmax(fmax(res.left, *max), res.right);
+ return res;
+}
+
+int longestZigZag(struct TreeNode *root) {
+ int max = 0;
+ process(root, &max);
+ return max;
+}