剑指offer-和为S的连续正数序列

class Solution {
public:
    vector<vector<int> > FindContinuousSequence(int sum) {
        vector<vector<int> > ans; 
        map<int, int> mp; 
        int t = 0, tmp =0; 
        mp[0] = 0; 
        for(int i=1; i<sum; ++i){
            t += i; 
            mp[t] = i; 
            tmp = t - sum; 
            if( mp.find( tmp ) != mp.end()){
                vector<int> a; 
                for(int j=mp[tmp]+1; j<=i; ++j){
                    a.push_back(j); 
                }
                ans.push_back(a); 
            }
        }
        return ans; 
    }
};