描述： Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.
For example,
If n = 4 and k = 2, a solution is:
[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ]
思路：模拟手工组合C(n,k)的方法， 用pos 标记当前的位置，从pos ，n 中间选取k个数据，
class Solution { public: void choose(int n, int k, int pos, vector<int>&array, vector<vector<int> >&ret) { if(k == 0) { ret.push_back(array); return; } for(int i = pos ; i <= n; ++i) { array.push_back(i); choose(n, k-1, i+1, array, ret); array.resize(array.size()-1); } return; } vector<vector<int> > combine(int n, int k) { vector<vector<int> > ret ; if(n == 0 || k == 0 || k > n) return ret; vector<int> array; choose(n, k, 1, array, ret); return ret; } };
Combinations [leetcode],布布扣,bubuko.com
原文地址：http://www.cnblogs.com/memoryh/p/3841258.html
