poj 1236 Network of Schools

来源：互联网发布：linux ansi 编辑：程序博客网时间：2024/05/27 20:50
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         do30         {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 }
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