c++ - 算法题：N个数中找M个数，其之和等于target

Question

LeetCode 上有一道M=2的题.
用两层循环遍历，O(n^2)可解。

但如果M=5或M=10呢，在这种情况下，除了盲搜外，有什么想对高效的方法吗？

Answer 1

Convert the problem into a 2 sum problem step by step.
According to this idea, the complexity that k sum can achieve is $$ O(n^{k-1}). $$

In addition, 2 sum can actually do $$ O(n) $$

Answer 2

After leetcode, there will be 4sum, 3sum questions, or 4sum converted to 3sum, 3sum to 2sum, after looking at the discussion forum, this idea is reliable

Answer 3

Isn’t it converted into two arrays, traversing one and dividing the other into two?
For example, m=7, traverse a 3n array, and then bisect another 4n array?
n^((m+1)/2)