0
1
mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-12-12 02:26:26 +00:00
OI-codes/Luogu/P1868/P1868.cpp
2022-04-03 16:45:27 +08:00

40 lines
720 B
C++

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