112. 路径总和

[rocksc30]

/**
 * 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 {
    public boolean hasPathSum(TreeNode root, int targetSum) {
        if(root == null) return false;
        return traversal(root, targetSum - root.val);
    }
    private boolean traversal(TreeNode root, int count){
        if(root.left == null && root.right == null && count == 0) return true;
        if(root.left == null && root.right == null) return false;
        if(root.left != null){
            if(traversal(root.left, count - root.left.val)) return true;
        }
        if(root.right != null){
            if(traversal(root.right, count - root.right.val)) return true;
        }
        return false;
    }
}

[rocksc30]

113. 路径总和 II

     /**
     * 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 {
     private List<List<Integer>> ans = new ArrayList<>();
     private Stack<Integer> path = new Stack<>();
     
     private void traveral(TreeNode root, int count){
         if (root.left == null && root.right == null && count == 0) {
             ans.add(new ArrayList(path));
             return;
         }
         if (root.left == null && root.right == null) {
             return;
         }
         if (root.left != null) {
             path.push(root.left.val);
             traveral(root.left, count - root.left.val);
             path.pop();
         }  
         if (root.right != null) {
             path.push(root.right.val);
             traveral(root.right, count - root.right.val);
             path.pop();
         }  
     }
     
     public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
         if (root == null) {
             return ans;
         }
         path.push(root.val);
         traveral(root, targetSum - root.val);
         return ans;
     }
     }