1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
| #include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#define maxn 30010
#define maxm 5010
#define INF 1000000000
using namespace std;
int n, m, s;
struct Edge {
int to, next, w;
} e[3 * maxn + maxm]; int c1, head[maxn];
inline void add_edge(int u, int v, int w) {
e[c1].to = v; e[c1].w = w;
e[c1].next = head[u]; head[u] = c1++;
}
int dis[maxn]; bool vis[maxn]; queue<int> Q;
void spfa(int s) {
fill(vis, vis + maxn, 0); vis[s] = 1; Q.push(s);
fill(dis, dis + maxn, -INF); dis[s] = 0;
while (!Q.empty()) {
int u = Q.front(); Q.pop(); vis[u] = 0;
for (int i = head[u]; ~i; i = e[i].next) {
int v = e[i].to, w = e[i].w;
if (dis[v] < dis[u] + w) {
dis[v] = dis[u] + w;
if (vis[v]) continue; vis[v] = 1;
Q.push(v);
}
}
}
}
int main() { fill(head, head + maxn, -1);
ios::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n >> m; s = n + 1;
for (int i = 1; i <= m; ++i) {
int x, y, z; cin >> x >> y >> z;
add_edge(x - 1, y, z);
}
for (int i = 0; i <= n; ++i) {
add_edge(s, i, 0); if (!i) continue;
add_edge(i - 1, i, 0); add_edge(i, i - 1, -1);
} spfa(s); cout << dis[n] << "\n";
return 0;
}
|