首页 > 代码库 > [LeetCode] Combination Sum II

[LeetCode] Combination Sum II

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, a1a2 ≤ … ≤ ak).
  • The solution set must not contain duplicate combinations.

For example, given candidate set 10,1,2,7,6,1,5 and target 8,
A solution set is:
[1, 7]
[1, 2, 5]
[2, 6]
[1, 1, 6]

以下是我 AC 的代码:

/** * author: Zhou J */class Solution {public:    vector<vector<int> > combinationSum2(vector<int> &num, int target)     {        sort(num.begin(), num.end());        vector<vector<int>> ret;        vector<int> path;        combinationSum2Rec(num, target, ret, path, 0);        return ret;    }    private:    void combinationSum2Rec(const vector<int> &num,                            const int target,                            vector<vector<int>> &ret,                            vector<int> &path,                            size_t pos)    {        if (target == 0)        {            ret.push_back(path);            return;        }                // Mark the previous one        int prev = -1;                for (size_t ix = pos; ix != num.size(); ++ix)        {            if (num[ix] > target)            {                break;            }                        if (prev == num[ix])            {                continue;            }                        path.push_back(num[ix]);            combinationSum2Rec(num, target - num[ix], ret, path, ix + 1);            // Backtracing. Note that we should sort the vector before we use the skill of backtracing.            path.erase(path.end() - 1);            // The one which we have pushed just now.             prev = num[ix];        }    }};

[LeetCode] Combination Sum II