leetcode 46. 全排列

leetcode

C++：

class Solution {
public:
    void backtrack(vector<vector<int>>& results, vector<int>& nums, int first, int length) {

        if ( first == length ) {

            results.push_back( nums );

            return;
        }

        for ( int i = first; i < length; ++i ) {

            std::swap( nums[i], nums[first] );
            backtrack( results, nums, first + 1, length );
            std::swap( nums[i], nums[first] );
        }
    }

    vector<vector<int>> permute(vector<int>& nums) {

        std::vector<std::vector<int>> results;
        backtrack( results, nums, 0, (int)nums.size() );

        return results;
    }
};