29 lines
781 B
C++
29 lines
781 B
C++
#include <vector>
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#include <unordered_map>
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/**
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* 1679. Max Number of K-Sum Pairs
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* You are given an integer array nums and an integer k.
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* In one operation, you can pick two numbers from the array whose sum equals k and remove them from the array.
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* Return the maximum number of operations you can perform on the array.
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*/
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class Solution {
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public:
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static int maxOperations(const std::vector<int>& nums, int k) {
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std::unordered_map<int, int> m;
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for (int i : nums)
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++m[i];
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int ret = (k & 1) ? 0 : (m[k / 2] / 2);
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const int pivot = (k & 1) ? (k / 2 + 1) : (k / 2);
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for (const auto& [idx, cnt] : m)
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if (idx < pivot && m.count(k - idx))
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ret += std::min(m[idx], m[k - idx]);
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return ret;
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}
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};
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int main() {
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Solution::maxOperations({2,2,2,3,1,1,4,1}, 4);
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}
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