LeetCode Combinations

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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：dfs搜索的类型，类似我们自己计算组合的情况，为了不重复我们必须不断的向前走

class Solution {
public:
    vector<vector<int> > ans;
    vector<int> tmp;

    void dfs(int cur, int dep, int n, int s) {
        if (cur == dep) {
            ans.push_back(tmp);
            return;
        }

        for (int i = s; i <= n; i++) {
            tmp[cur] = i;
            dfs(cur+1, dep, n, i+1);
        }
    }

    vector<vector<int> > combine(int n, int k) {
        tmp.resize(k);     
        ans.clear();
        dfs(0, k, n, 1);
        return ans;
    }
};

LeetCode Combinations

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原文地址：http://blog.csdn.net/u011345136/article/details/44922319