Combinations(leetcode)
阿新 • • 發佈:2018-11-09
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],]
沒什麼獨創的,就是組合問題的輸出,上面的演算法只是需要注意一下n == k時應該直接在存入全序列後即返回,否則在內部while迴圈會陷入死迴圈(或者可以修改下內部迴圈則可以只需要一個return語句即可)。class Solution { public: vector<vector<int> > combine(int n, int k) { vector<vector<int> > Martrix; vector<int> temp; for( int i = 0;i < k;++i ) temp.push_back(i+1); Martrix.push_back(temp); if( n == k ) return Martrix; do{ int t = k - 1,r = n; while( temp[t] == r ) { t--; r--; } temp[t]++; for( int i = t + 1;i < k;++i ) temp[i] = temp[i-1] + 1; Martrix.push_back(temp); }while( temp[0] != n - k + 1 ); return Martrix; } };