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## Discussion of Problem 1306. Sequence Median

I've tried everything but still MLE
Posted by achvanov 30 Mar 2019 12:36
I've tried priority_queue and heap, but still MLE. Here's my code, can somebody help me?
#include <iostream>
#include <algorithm>
#include <vector>
int main() {
int n, a;
std::cin >> n;
std::vector<int> v(n / 2 + 1);
for (int i = 0; i < n / 2 + 1; ++i) {
std::cin >> v[i];
}
std::make_heap(v.begin(), v.end());
for (int i = 0; i < (n + 1) / 2 - 1; ++i) {
std::cin >> a;
v.push_back(a);
std::push_heap(v.begin(), v.end());
std::pop_heap(v.begin(), v.end());
v.pop_back();
}
std::sort_heap(v.begin(), v.end());
if (n % 2) {
std::cout << v.back() << ".0";
}
else {
a = v.back();
v.pop_back();
std::cout << (0ll + a + v.back()) / 2 << '.';
if ((0ll + a + v.back()) % 2) {
std::cout << 5;
}
else {
std::cout << 0;
}
}

return 0;
}
It's WA.
Posted by lnxdx 9 Sep 2019 22:16
It's wrong. Because the last leaf of the max heap is not necessarily minimum but you are removing it (v.pop_back();). Your code may remove the median element.

And the sort_heap has no effect.