fd

Author: dingjikerbo

leetcode/solution/src/LongestUnivaluePath.java

@@ -0,0 +1,27 @@
+public class LongestUnivaluePath {
+
+    public int longestUnivaluePath(TreeNode root) {
+        int[] res = new int[1];
+        dfs(root, res);
+        return res[0];
+    }
+
+    private int dfs(TreeNode node, int[] res) {
+        if (node == null) {
+            return 0;
+        }
+        int left = dfs(node.left, res);
+        int right = dfs(node.right, res);
+
+        int lval = 0, rval = 0;
+
+        if (node.left != null && node.left.val == node.val) {
+            lval = left + 1;
+        }
+        if (node.right != null && node.right.val == node.val) {
+            rval = right + 1;
+        }
+        res[0] = Math.max(res[0], lval + rval);
+        return Math.max(lval, rval);
+    }
+}