AcWing 853. 有边数限制的最短路
原题链接
简单
作者:
qgc123
,
2021-12-05 23:28:58
,
所有人可见
,
阅读 165
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
const int N = 510, M = 10010;
int n,m,k;
struct ed
{
int a, b, c;
}edge[M];
int d[N], la[N];
void bellman_ford(){
memset(d, 0x3f, sizeof d);
d[1] = 0;
for (int i = 0; i < k;i++){
memcpy(la, d, sizeof(d));
for (int j = 0; j < m;j++){
auto e= edge[j];
d[e.b] = min(d[e.b], la[e.a] + e.c);
}
}
}
int main(){
cin >> n >> m >> k;
for(int i=0;i<m;i++){
int a, b, c;
cin >> a >> b >> c;
edge[i] = {a, b, c};
}
bellman_ford();
if(d[n]>0x3f3f3f3f/2)
cout << "impossible" << endl;
else{
cout << d[n] << endl;
}
return 0;
}