LeetCode Solutions : Path Sum I & II

标签：leetcode   java   algorithms   datastructure   path   

Path Sum

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean hasPathSum(TreeNode root, int sum) {
        if(root==null)
			return false;
		if(root.left==null&&root.right==null)
			return sum==root.val?true:false;
		return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);
    }
}

Path Sum II 

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ArrayList<ArrayList<Integer>> pathSum(TreeNode root, int sum) {
        ArrayList<ArrayList<Integer>> results=new ArrayList<ArrayList<Integer>>();
		if(root==null)
			return results;
		helper(results,new ArrayList<Integer>(),root,sum);
		return results;
    }
    private void helper(ArrayList<ArrayList<Integer>> results,ArrayList<Integer> path,TreeNode root,int sum){
		if(root==null)
			return;
		path.add(root.val);
		if(root.left==null&&root.right==null){
			if(root.val==sum){
				ArrayList<Integer> temp=new ArrayList<Integer>(path);
				results.add(temp);
			}
		}
		helper(results,path,root.left,sum-root.val);
		helper(results,path,root.right,sum-root.val);
		path.remove(path.size()-1);
	}
}

LeetCode Solutions : Path Sum I & II

标签：leetcode   java   algorithms   datastructure   path   

原文地址：http://blog.csdn.net/lviiii/article/details/39294363