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
1 #include <cstdio> 2 #include <cstring> 3 #include <iostream> 4 #define N 200001 5 6 int n, k, cnt; 7 long long ans, dis[N]; 8 int head[N], to[N << 1], val[N << 1], next[N << 1]; 9 bool vis[N]; 10 11 inline int read() 12 { 13 int x = 0, f = 1; 14 char ch = getchar(); 15 for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1; 16 for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0'; 17 return x * f; 18 } 19 20 inline void add(int x, int y, int z) 21 { 22 to[cnt] = y; 23 val[cnt] = z; 24 next[cnt] = head[x]; 25 head[x] = cnt++; 26 } 27 28 inline bool spfa(int u) 29 { 30 int i, v; 31 vis[u] = 1; 32 for(i = head[u]; i ^ -1; i = next[i]) 33 { 34 v = to[i]; 35 if(dis[v] > dis[u] + val[i]) 36 { 37 dis[v] = dis[u] + val[i]; 38 if(vis[v]) return 0; 39 else if(!spfa(v)) return 0; 40 } 41 } 42 vis[u] = 0; 43 return 1; 44 } 45 46 int main() 47 { 48 int i, j, x, y, z; 49 n = read(); 50 k = read(); 51 memset(head, -1, sizeof(head)); 52 for(i = n; i >= 1; i--) add(0, i, -1); 53 for(i = 1; i <= k; i++) 54 { 55 z = read(); 56 x = read(); 57 y = read(); 58 if(z == 1) add(x, y, 0), add(y, x, 0); 59 if(z == 2) 60 { 61 add(x, y, -1); 62 if(x == y) 63 { 64 puts("-1"); 65 return 0; 66 } 67 } 68 if(z == 3) add(y, x, 0); 69 if(z == 4) 70 { 71 add(y, x, -1); 72 if(x == y) 73 { 74 puts("-1"); 75 return 0; 76 } 77 } 78 if(z == 5) add(x, y, 0); 79 } 80 if(spfa(0)) 81 { 82 for(i = 1; i <= n; i++) ans -= dis[i]; 83 printf("%lld ", ans); 84 } 85 else puts("-1"); 86 return 0; 87 }