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https://git.sb/baoshuo/OI-codes.git
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73 lines
1.5 KiB
C++
73 lines
1.5 KiB
C++
#include <iostream>
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#include <limits>
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#include <queue>
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#include <vector>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 100005;
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int n, k, a[N], pre[N], suf[N];
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long long c[N], ans;
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std::priority_queue<
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std::pair<int, long long>,
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std::vector<std::pair<int, long long>>,
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auto(*)(std::pair<int, long long>, std::pair<int, long long>)->bool>
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q([](std::pair<int, long long> a, std::pair<int, long long> b) -> bool {
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return a.second > b.second;
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});
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> k;
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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}
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for (int i = 1; i < n; i++) {
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c[i] = static_cast<long long>(a[i + 1]) - a[i];
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pre[i] = i - 1;
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suf[i] = i + 1;
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}
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suf[n - 1] = 0;
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for (int i = 1; i < n; i++) {
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q.emplace(i, c[i]);
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}
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while (k--) {
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auto o = q.top();
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q.pop();
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if (o.second != c[o.first]) {
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k++;
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continue;
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}
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ans += o.second;
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int l = pre[o.first],
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r = suf[o.first];
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suf[o.first] = suf[r];
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pre[suf[o.first]] = o.first;
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pre[o.first] = pre[l];
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suf[pre[o.first]] = o.first;
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c[o.first] = (l && r) ? std::min(static_cast<long long>(std::numeric_limits<int>::max()), c[l] + c[r] - c[o.first]) : std::numeric_limits<int>::max();
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c[l] = c[r] = std::numeric_limits<int>::max();
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q.emplace(o.first, c[o.first]);
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}
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cout << ans << endl;
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return 0;
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}
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