LeetCode 77. Combinations

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],
]

题目大意:给两个整数n和k,返回所有的k个数字组合,这些数字只能从1…n中选择~

分析:从cur == 0,cnt == 0开始,每次将cur + 1 ~ n之间的数字放入row中,并将cnt + 1,然后继续深度优先搜索直到cnt == k为止将row放入result中作为结果之一,不要忘记dfs遍历后还要将当前元素pop_back()出来,最后返回result~