强联通分量模版题，tarjan算法：
1 #include<stdio.h> 2 #include<string.h> 3 #define MAXN 110 4 5 int n, p, ans1, ans2, u[MAXN*MAXN], v[MAXN*MAXN], next[MAXN*MAXN], first[MAXN]; 6 int dfn[MAXN], low[MAXN], col[MAXN], stk[MAXN], ins[MAXN], ind, top, cols, tmp; 7 int indg[MAXN], outdg[MAXN], zeroin, zeroout; 8 9 void dfs(int u) 10 { 11 dfn[u] = low[u] = ++ind; 12 stk[++top] = u, ins[u] = 1; 13 for(int i = first[u]; i != -1; i = next[i]) 14 { 15 int ve = v[i]; 16 if(!dfn[ve]) 17 { 18 dfs(ve); 19 if(low[ve] < low[u]) low[u] = low[ve]; 20 } 21 else if(ins[ve]) 22 { 23 if(dfn[ve] < low[u]) low[u] = dfn[ve]; 24 } 25 } 26 if(dfn[u] == low[u]) 27 { 28 cols ++; 29 do 30 { 31 tmp = stk[top--]; 32 col[tmp] = cols; 33 ins[tmp] = 0; 34 } 35 while(tmp != u); 36 } 37 } 38 39 void tarjan(int n) 40 { 41 memset(dfn, 0, sizeof(dfn)); 42 memset(low, 0, sizeof(low)); 43 memset(col, 0, sizeof(col)); 44 memset(stk, 0, sizeof(stk)); 45 memset(ins, 0, sizeof(ins)); 46 ind = top = cols = 0; 47 for(int i = 1; i <= n; i ++) 48 { 49 if(!dfn[i]) dfs(i); 50 } 51 if(cols == 1) 52 { 53 ans1 = 1, ans2 = 0; 54 return; 55 } 56 ans1 = ans2 = zeroin = zeroout = 0; 57 memset(indg, 0, sizeof(indg)); 58 memset(outdg, 0, sizeof(outdg)); 59 for(int u = 1; u <= n; u ++) 60 { 61 for(int i = first[u]; i != -1; i = next[i]) 62 { 63 int ve = v[i]; 64 if(col[u] == col[ve]) continue; 65 indg[col[ve]] ++; 66 outdg[col[u]] ++; 67 } 68 } 69 for(int i = 1; i <= cols; i ++) 70 { 71 if(indg[i] == 0) zeroin ++; 72 if(outdg[i] == 0) zeroout ++; 73 } 74 ans1 = zeroin; 75 ans2 = zeroin > zeroout ? zeroin : zeroout; 76 } 77 78 int main() 79 { 80 while(~scanf("%d",&n)) 81 { 82 memset(first, -1, sizeof(first)); 83 p = 0; 84 for(int i = 1; i <= n; i ++) 85 while(1) 86 { 87 int a; 88 scanf("%d",&a); 89 if(a == 0) break; 90 u[p] = i; v[p] = a; 91 next[p] = first[u[p]]; 92 first[u[p]] = p; 93 p ++; 94 } 95 tarjan(n); 96 printf("%d\n%d\n",ans1, ans2); 97 } 98 return 0; 99 }