33 lines
818 B
C++
33 lines
818 B
C++
#include <vector>
|
|
#include <cstdio>
|
|
#include <unordered_map>
|
|
|
|
/**
|
|
* 454. 4Sum II
|
|
* Given four integer arrays nums1, nums2, nums3, and nums4 all of length n, return the number of tuples (i, j, k, l) such that:
|
|
* 0 <= i, j, k, l < n
|
|
* nums1[i] + nums2[j] + nums3[k] + nums4[l] == 0
|
|
*/
|
|
|
|
class Solution {
|
|
public:
|
|
static int fourSumCount(const std::vector<int>& nums1, const std::vector<int>& nums2, const std::vector<int>& nums3, const std::vector<int>& nums4) {
|
|
int ret = 0;
|
|
std::unordered_map<int, int> m1, m2;
|
|
for (int i : nums1)
|
|
for (int j : nums2)
|
|
++m1[i + j];
|
|
for (int i : nums3)
|
|
for (int j : nums4)
|
|
++m2[i + j];
|
|
for (const auto& p : m1)
|
|
ret += p.second * m2[-p.first];
|
|
return ret;
|
|
}
|
|
};
|
|
|
|
int main() {
|
|
std::printf("%d\n", Solution::fourSumCount({0}, {0}, {0}, {0}));
|
|
return 0;
|
|
}
|