LeetCode 39. Combination Sum

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

去重，自己写比用ＳＴＬ　ｓｅｔ处理快一些

哎，当初上交的保研复试题就是这个，这个第二题，第三题是一个不会的ｄｐ．．．．．．

const int SIZE = 1000+5;

class Solution {
public:
    void removeReplication(vector <int>& candidates) {
        vector <int> old(candidates);
        candidates.clear();
        if(old.size() == 0)return ;
        int pre = old[0];
        candidates.push_back(pre);
        for(int i=1;i<old.size();i++) {
            if(old[i] != pre) {
                candidates.push_back(old[i]);
                pre = old[i];
            }
        }
    }

    vector< vector<int> > combinationSum(vector<int>& candidates, int target) {
        ans.clear();
        sort(candidates.begin(), candidates.end());
        removeReplication(candidates);
        for(int i=0;i<candidates.size();i++)
            cnt[i] =  0;
        dfs(0,target, 0, candidates);
        return ans;
    }
    void dfs(int now, int target, int ptr, vector<int>& candidates) {
        if(now == target) {
                vector <int> ivec;//(cnt, cnt+candidates.size());
                for(int i=0;i<ptr;i++) {
                    for(int j=0;j<cnt[i];j++)
                        ivec.push_back(candidates[i]);
                }
                if(ans.size() == 0) {
                    ans.push_back(ivec);
                } else {
                    if(ivec != ans[ans.size()-1])ans.push_back(ivec);
                }
                return;
        }
        if(ptr >= candidates.size()|| now > target) return;
        int up = (target-now)/candidates[ptr];
        for(int i=0;i<=up;i++) {
            cnt[ptr] = i;
            dfs(now+i*candidates[ptr], target, ptr+1, candidates);
            cnt[ptr] = 0;
        }
    }
    int cnt[SIZE];
    vector < vector<int> > ans;
};