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40 lines
720 B
C++
40 lines
720 B
C++
#include <iostream>
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#include <limits>
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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 = 1.5e5 + 5,
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M = 3e6 + 5;
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int n, f[M], e[M];
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int l = std::numeric_limits<int>::max(),
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r = std::numeric_limits<int>::min();
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std::pair<int, int> a[N];
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bool vis[M];
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int main() {
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std::ios::sync_with_stdio(false);
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cin >> n;
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for (int i = 1, x, y; i <= n; i++) {
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cin >> x >> y;
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r = std::max(r, y);
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e[x] = y;
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vis[x] = true;
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}
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for (int i = r; i; i--) {
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if (vis[i]) {
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f[i] = std::max(f[i + 1], f[e[i] + 1] + (e[i] - i + 1));
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} else {
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f[i] = f[i + 1];
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}
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}
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cout << f[1] << endl;
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return 0;
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}
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