面试题 16.24. 数对和
难度中等
设计一个算法,找出数组中两数之和为指定值的所有整数对。一个数只能属于一个数对。
示例 1:
输入: nums = [5,6,5], target = 11
输出: [[5,6]]
示例 2:
输入: nums = [5,6,5,6], target = 11
输出: [[5,6],[5,6]]
提示:
* nums.length <= 100000
思路1.0:
设置map<int val,int num> rst,意为val值出现的次数num,将nums中的所有信息转移到rst中。通过遍历rst,同时减去当前遍历值和其配对值的num,并把这对数加入到rst中。
代码1.0:
class Solution {
public:
vector<vector<int>> pairSums(vector<int>& nums, int target) {
if (nums.empty()) return {};
map<int, int>rst;
vector<vector<int>> ans;
for (const auto& i : nums) {
rst[i]++;
}
for (auto& i : rst) {
if (i.second == 0) continue;
if (target - i.first == i.first) {
int time = i.second / 2;
for (int k = 0; k < time; ++k) {
ans.push_back(vector<int>({ i.first,i.first }));
}
i.second = 0;
}
else {
auto mery = rst.find(target - i.first);
int time = min(i.second, mery->second);
for (int k = 0; k < time; ++k) {
ans.push_back(vector<int>({ i.first,mery->first }));
}
i.second = 0;
mery->second = 0;
}
}
return ans;
}
};
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiIyVGduV2YfNWawNyROBlL5gTM5UDO1ATM0IDMxAjMwIzLc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)