[luoguP3275] [SCOI2011]糖果（差分约束）

传送门

差分约束裸题

但是坑！

有一个点是长为10W的链，需要逆序加边才能过（真是玄学）

还有各种坑爹数据

开longlong

——代码

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #define N 200001

 int n, k, cnt;
 long long ans, dis[N];
 int head[N], to[N << ], val[N << ], next[N << ];
 bool vis[N];

 inline int read()
 {
     int x = , f = ;
     char ch = getchar();
     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -;
     for(; isdigit(ch); ch = getchar()) x = (x << ) + (x << ) + ch - '';
     return x * f;
 }

 inline void add(int x, int y, int z)
 {
     to[cnt] = y;
     val[cnt] = z;
     next[cnt] = head[x];
     head[x] = cnt++;
 }

 inline bool spfa(int u)
 {
     int i, v;
     vis[u] = ;
     for(i = head[u]; i ^ -; i = next[i])
     {
         v = to[i];
         if(dis[v] > dis[u] + val[i])
         {
             dis[v] = dis[u] + val[i];
             if(vis[v]) return ;
             else if(!spfa(v)) return ;
         }
     }
     vis[u] = ;
     return ;
 }

 int main()
 {
     int i, j, x, y, z;
     n = read();
     k = read();
     memset(head, -, sizeof(head));
     for(i = n; i >= ; i--) add(, i, -);
     for(i = ; i <= k; i++)
     {
         z = read();
         x = read();
         y = read();
         if(z == ) add(x, y, ), add(y, x, );
         if(z == )
         {
             add(x, y, -);
             if(x == y)
             {
                 puts("-1");
                 return ;
             }
         }
         if(z == ) add(y, x, );
         if(z == )
         {
             add(y, x, -);
             if(x == y)
             {
                 puts("-1");
                 return ;
             }
         }
         if(z == ) add(x, y, );
     }
     if(spfa())
     {
         for(i = ; i <= n; i++) ans -= dis[i];
         printf("%lld\n", ans);
     }
     else puts("-1");
     return ;
 }