Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.
Each number in candidates may only be used once in the combination.
Note:
- All numbers (including
target) will be positive integers. - The solution set must not contain duplicate combinations.
Example 1:
Input: candidates =[10,1,2,7,6,1,5], target =8, A solution set is: [ [1, 7], [1, 2, 5], [2, 6], [1, 1, 6] ]
Example 2:
Input: candidates = [2,5,2,1,2], target = 5, A solution set is: [ [1,2,2], [5] ]
这道题跟之前那道 Combination Sum 本质没有区别，只需要改动一点点即可，之前那道题给定数组中的数字可以重复使用，而这道题不能重复使用，只需要在之前的基础上修改两个地方即可，首先在递归的 for 循环里加上 if (i > start && num[i] == num[i - 1]) continue; 这样可以防止 res 中出现重复项，然后就在递归调用 helper 里面的参数换成 i+1，这样就不会重复使用数组中的数字了，代码如下：
class Solution { public: vector<vector<int>> combinationSum2(vector<int>& num, int target) { vector<vector<int>> res; vector<int> out; sort(num.begin(), num.end()); helper(num, target, 0, out, res); return res; } void helper(vector<int>& num, int target, int start, vector<int>& out, vector<vector<int>>& res) { if (target < 0) return; if (target == 0) { res.push_back(out); return; } for (int i = start; i < num.size(); ++i) { if (i > start && num[i] == num[i - 1]) continue; out.push_back(num[i]); helper(num, target - num[i], i + 1, out, res); out.pop_back(); } } };
Github 同步地址：
https://github.com/grandyang/leetcode/issues/40
类似题目：
参考资料：