[leetcode] permutations

1077 단어
Given a collection of numbers, return all possible permutations.
For example, [1,2,3]  have the following permutations: [1,2,3][1,3,2][2,1,3][2,3,1][3,1,2] , and  [3,2,1] . 가장 간단한 것은 귀속적인 방법으로 해결하는 것이다.
class Solution {
public:
    vector<vector<int> > permute(vector<int> &num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int> >ret;
        int n=num.size();
        _permute(num,n,n-1,ret);
        return ret;
    }
    void _permute(vector<int>& array,int n,int depth,vector<vector<int> >&ret){
        if(depth==0){
            ret.push_back(array);
            return;
        }
        for(int i=0 ; i<=depth ; i++){
            swap(array[i],array[depth]);
            _permute(array,n,depth-1,ret);
            swap(array[i],array[depth]);
        }
        return;        
    }
};

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