双联通分量、割点

M.cpp

@@ -0,0 +1,82 @@
+#include <iostream>
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+ 
+/* wuxiangtugediangebian */
+const int MAXN = 1010;
+const int WHITE = 0,GREY = 1,BLACK = 2;
+int map[MAXN][MAXN];
+int DFN[MAXN],low[MAXN],col[MAXN];
+int target[MAXN];
+int n,ans;
+void tarjan(int now, int father, int depth){
+    DFN[now] = depth;
+    col[now] = GREY;
+    int child = 0;
+    ans = 0;
+    for(int i = 1; i <= n; i++){
+        if(map[now][i] == 0)continue;
+ 
+        if( i != father && col[i] == GREY){// i is u'grandfather
+            low[now] = min(low[now],DFN[i]);
+        }
+        if(col[i] == WHITE ){// i is u'child
+            tarjan(i,now,depth+1);
+            child++;
+            low[now] = min(low[i],low[now]);
+            if((now == 1 && child > 1) || (now != 1 && low[i] >= DFN[now])){//is ge dian
+                target[now] ++;
+                //ans++;  //注意：需要记录该割点增加几个联通分量的操作需要在这里ans++
+            }
+            /*
+            if(low[i] > DEN[now]){
+                target[now][i] = 1;//now->i is ge edge;
+            }
+            */
+        }
+    }
+    col[now] = BLACK;
+}
+int main(){
+    int T= 0;
+    int x,y;
+    while(scanf("%d",&x)&&x){
+        memset(map,0,sizeof(map));
+        memset(col,0,sizeof(col));
+        memset(target,0,sizeof(target));
+        for(int i = 1; i <= MAXN; i++){
+            low[i] = 99999999;//low[i] should initilized INT_MAX;
+        }
+        n = max(n,x);
+        scanf("%d",&y);
+        n = max(n,y);
+        map[x][y] = map[y][x] = 1;
+        while(scanf("%d",&x)&&x){
+            n = max(n,x);
+            scanf("%d",&y);
+            n = max(n,y);
+            map[x][y] = map[y][x] = 1;
+        }
+        printf("Network #%d\n",++T);
+        tarjan(1,1,0);
+        int cnt = 0;
+        for(int i = 1; i <= n; i++){
+            if(target[i]) {
+                    cnt++;
+            }
+        }
+        if(cnt == 0){
+            printf("  No SPF nodes\n");
+        }
+        else{
+            for(int i = 1; i <= n; i++){
+                if(target[i]) {
+                        printf("  SPF node %d leaves %d subnets\n",i,target[i]+1);
+                }
+            }
+        }
+        cout<<endl;
+    }
+}