[leetcode] Combination Sum II

標籤：des   class   blog   code   java   http   

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

• All numbers (including target) will be positive integers.
• Elements in a combination (a1, a2, … , ak) must be in non-descending order. (ie, a1 ≤ a2 ≤ … ≤ ak).
• The solution set must not contain duplicate combinations.

For example, given candidate set10,1,2,7,6,1,5and target8,
A solution set is:
[1, 7]
[1, 2, 5]
[2, 6]

[1, 1, 6]

https://oj.leetcode.com/problems/combination-sum-ii/

import java.util.ArrayList;import java.util.Arrays;public class Solution {public ArrayList<ArrayList<Integer>> combinationSum2(int[] num,int target) {ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();if (num == null || num.length == 0)return result;int n = num.length;Arrays.sort(num);ArrayList<Integer> list = new ArrayList<Integer>();dfs(0, num, target, list, result);return result;}private void dfs(int level, int[] a, int num, ArrayList<Integer> list,ArrayList<ArrayList<Integer>> result) {if (num == 0) {result.add(new ArrayList<Integer>(list));} else if (num < 0)return;else {for (int i = level; i < a.length; i++) {if (a[i] <= num) {list.add(a[i]);dfs(i + 1, a, num - a[i], list, result);list.remove(list.size() - 1);while (i < a.length - 1 && a[i] == a[i + 1])i++;}}}}public static void main(String[] args) {System.out.println(new Solution().combinationSum2(new int[] { 10, 1, 2,7, 6, 1, 5 }, 8));System.out.println(new Solution().combinationSum2(new int[] { 1, 1, 1,2, 2 }, 3));}}

 

 

參考：

http://blog.csdn.net/linhuanmars/article/details/20829099