leetcode 373. Find K Pairs with Smallest Sums

373. Find K Pairs with Smallest Sums

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. 

Define a pair (u,v) which consists of one element from the first array and one element from the second array.

Find the k pairs (u1,v1),(u2,v2) ...(uk,vk) with the smallest sums.

Example 1:

Given nums1 = [1,7,11], nums2 = [2,4,6],  k = 3Return: [1,2],[1,4],[1,6]The first 3 pairs are returned from the sequence:[1,2],[1,4],[1,6],[7,2],[7,4],[11,2],[7,6],[11,4],[11,6]

Example 2:

Given nums1 = [1,1,2], nums2 = [1,2,3],  k = 2Return: [1,1],[1,1]The first 2 pairs are returned from the sequence:[1,1],[1,1],[1,2],[2,1],[1,2],[2,2],[1,3],[1,3],[2,3]

Example 3:

Given nums1 = [1,2], nums2 = [3],  k = 3 Return: [1,3],[2,3]All possible pairs are returned from the sequence:[1,3],[2,3]

1、疯狂利用map的排序功能。

class Solution {public:    vector<pair<int, int>> kSmallestPairs(vector<int>& nums1, vector<int>& nums2, int k)     {        vector<pair<int, int>> ret;        multimap<int, pair<int, int>> mp;        for (auto i : nums1)        {            for (auto j : nums2)            {                mp.insert(pair<int,pair<int, int> >(i+j, make_pair(i, j)));            }        }        for (auto it = mp.begin(); it != mp.end(); it++)        {            ret.push_back(it->second);            if (--k == 0) break;        }        return ret;    }};