public class Solution { public static void main(String[] args) { int[] candidates = { 5, 5, 10, 2, 3 }; int target = 15; List<List<Integer>> res = combinationSum(candidates, target); for (List<Integer> list : res) { System.out.println(list); } } public static List<List<Integer>> combinationSum(int[] num, int target) { List<List<Integer>> result = new ArrayList<List<Integer>>(); Arrays.sort(num); Stack<Integer> stk = new Stack<Integer>(); findCombination(result, 0, target, stk, num); return result; } private static void findCombination(List<List<Integer>> result, int index, int target, Stack<Integer> stk, int[] num) { if (target == 0) { result.add(new ArrayList<Integer>(stk)); return; } else { for (int i = index; i < num.length; i++) { if (num[i] > target) return; stk.push(num[i]); findCombination(result, i + 1, target - num[i], stk, num); stk.pop(); } } } } 先对数组排序，然后利用一个栈，递归。