62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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// 这里也可以把[a,b]区间往右移动一个单位，
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// 这样就可以空出来S[0]这个点，作为超级原点
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const int N = 50010, M = N * 3 + 10;
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int dist[N];
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int m; // m个区间，可以理解为m条边
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bool st[N];
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// 邻接表
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int e[M], h[N], idx, w[M], ne[M];
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void add(int a, int b, int c) {
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e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
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}
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void spfa() {
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queue<int> q;
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// 求最大路径长度
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memset(dist, -0x3f, sizeof dist);
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dist[0] = 0;
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st[0] = true;
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q.push(0);
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while (q.size()) {
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int u = q.front();
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q.pop();
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st[u] = false;
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for (int i = h[u]; ~i; i = ne[i]) {
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int v = e[i];
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if (dist[v] < dist[u] + w[i]) {
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dist[v] = dist[u] + w[i];
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if (!st[v]) {
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q.push(v);
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st[v] = true;
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}
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}
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}
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}
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}
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int main() {
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cin >> m;
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memset(h, -1, sizeof h);
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/*
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① s(i) >= s(i-1) + 0
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② s(i-1)>= s(i) - 1
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*/
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for (int i = 1; i < N; i++) add(i - 1, i, 0), add(i, i - 1, -1);
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while (m--) {
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int a, b, c;
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cin >> a >> b >> c;
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a++, b++;
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add(a - 1, b, c); // s(b) >= s(a-1) + c
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}
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spfa();
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printf("%d\n", dist[50001]);
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return 0;
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}
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