题目链接:https://www.luogu.org/problemnew/show/P1186
邻接表开大开小真的奇妙,毒瘤玩意,再您妈的见。
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1010;
const int inf = 2139062143;
struct edge{
int len, from, to, next;
}e[1000001];
int head[maxn], dis[maxn], n, m, cnt, u, v, w, ans, s, cut[maxn][maxn], f[maxn];//f[]记录路径
bool vis[maxn], flag;
queue<int> q;
void add(int u, int v, int w)
{
e[++cnt].from = u;
e[cnt].len = w;
e[cnt].to = v;
e[cnt].next = head[u];
head[u] = cnt;
}
int SPFA()
{
queue<int> q;
memset(vis,0,sizeof(vis));
memset(dis,0x3f3f3f3f,sizeof(dis));
vis[1] = 1;
q.push(1);
dis[1] = 0;
while(!q.empty())
{
int now = q.front();
q.pop();
vis[now] = 0;
for(int i = head[now]; i ; i = e[i].next)
{
if(cut[now][e[i].to] == 0&&dis[e[i].to] > dis[now]+e[i].len)
{
if(!flag) f[e[i].to] = now;
dis[e[i].to] = dis[now]+e[i].len;
if(!vis[e[i].to])
{
vis[e[i].to] = 1;
q.push(e[i].to);
}
}
}
}
}
int main()
{
scanf("%d%d",&n,&m);
memset(dis,0x7f,sizeof(dis));
for(int i = 1; i <= m; i++)
{
scanf("%d%d%d",&u,&v,&w);
add(u,v,w);
add(v,u,w);
}
SPFA();
flag = 1;
for(int i = n; i != 1; i = f[i])
{
cut[f[i]][i] = 1;
cut[i][f[i]] = 1;
SPFA();
cut[f[i]][i] = 0;
cut[i][f[i]] = 0;
ans = max(dis[n], ans);
}
printf("%d
",ans);
return 0;
}