Time: 0 ms (100%), Space: 44.8 MB (73.8%) - LeetHub

Author: SHIMHUN

LeetCode/Easy/0112-path-sum/0112-path-sum.java

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+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    int targetSum;
+
+    public boolean hasPathSum(TreeNode root, int targetSum) {
+        this.targetSum=targetSum;
+        if(root == null) return false;
+
+        return dfs(root, root.val);
+    }
+
+    boolean dfs(TreeNode node, int currSum){
+
+        //리프 도착
+        if(node.left==null && node.right==null){
+            // if(currSum == targetSum) return true;
+            return currSum == targetSum;
+        }
+
+        if(node.left!=null && dfs(node.left, currSum+node.left.val)) return true;
+        if(node.right!=null && dfs(node.right, currSum+node.right.val)) return true;
+
+        return false;
+    }
+}