Path Sum | LeetCode | Java

According to the problem we have to find the sum from every root-to-leaf path and check whether it is equal to the targetSum.
So, the intuitive code will be

class Solution {
    public boolean hasPathSum(TreeNode root, int targetSum) {
        return pathSum(root, 0, targetSum);
    }

    boolean pathSum(TreeNode node, int sum, int targetSum){
        if(node==null)
            return false;

        sum += node.val;

        if(sum==targetSum)
            return true;

        return pathSum(node.left, sum, targetSum) || pathSum(node.right, sum, targetSum);

    }
}

Verdict : 100 / 117 test cases passed.

Hidden test case gives the clear picture of the entirety of the question.

Our sum should not be just based on node value but root-to-leaf path.
After reaching the leaf node only are we allowed to take the sum of it.
So, the code modifies slightly.

class Solution {
    public boolean hasPathSum(TreeNode root, int targetSum) {
        return pathSum(root, 0, targetSum);
    }

    boolean pathSum(TreeNode node, int sum, int targetSum){
        if(node==null)
            return false;

        sum += node.val;

        //we are adding the condition to identify leaf node. If node.left and node.right==null indicates the "Leaf Node"

        if(node.left==null && node.right==null && sum==targetSum)
            return true;

        return pathSum(node.left, sum, targetSum) || pathSum(node.right, sum, targetSum);

    }
}

Thanks for reading :)
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Path Sum | LeetCode | Java

Tanuja V

Verdict : 100 / 117 test cases passed.

Hidden test case gives the clear picture of the entirety of the question.

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