Chen-tao

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {

Chen-tao

// https://leetcode.com/problems/subsets-ii/
public class Solution {
    
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();
    
    //public static int[] path = new int[100];
    
    public static boolean[] v = new boolean[100];
    
    public static void robot(int idx, int[] nums){

Chen-tao

//https://leetcode.com/problems/subsets/
//深搜 框架解法
public class Solution {
    
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();
    
    //public static int[] path = new int[100];
    
    public static boolean[] v = new boolean[100];
    

Chen-tao

//https://leetcode.com/problems/subsets/
//一种思路
public class Solution {
    /*
     * Given a set S of n distinct integers, there is a relation between Sn and Sn-1. The subset
     * of Sn is the union of subset of Sn-1 and each element in Sn-1 + one more element.
     * Therefore, a Java solution can be quickly formalized.
     */
     
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();

Chen-tao

//https://leetcode.com/problems/combinations/
// 深度优先搜索框架
public class Solution {
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();
    
    public static int[] path = new int[100];
    
    public static int K = 0;
    
    public static void robot(int idx, int n, int k){//idx [0, n] 

Chen-tao

package algorithm.sort;
 
class ListNode {
	int val;
	ListNode next;
 
	ListNode(int x) {
		val = x;
		next = null;
	}

Chen-tao

//https://leetcode.com/problems/permutations/
/**
 * 深度优先搜索框架
 */
public class Solution {
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();
    
    public static int[] path = new int[100];
    
    public static boolean[] v = new boolean[100];

Chen-tao

//https://leetcode.com/problems/path-sum/
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */

Chen-tao

//https://leetcode.com/problems/reverse-words-in-a-string/
// O(1) space v
public void reverseWords(char[] s) {
    int i=0;
    for(int j=0; j<s.length; j++){
        if(s[j]==' '){
            reverse(s, i, j-1);        
            i=j+1;
        }
    }

Chen-tao

//https://leetcode.com/problems/reverse-words-in-a-string/
public class Solution {
    public String reverseWords(String s) {
        
		if (s == null || s.length() == 0) {
			return "";
		}
		StringBuilder ans = new StringBuilder();
		s = s.trim().replaceAll(" +", " ");
		String[] anss = s.split(" ");