mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
106 lines
2.3 KiB
C++
106 lines
2.3 KiB
C++
#include <cstdio>
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#include <cstring>
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#include <string>
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#include <iostream>
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#include <algorithm>
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using namespace std;
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const int N = 1050, M = 21000;
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struct EDGE
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{
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int u, v, next;
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}edge[M];
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int num, head[N], low[N], lp[N], step;
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int n, m, ans=0, f, root;
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void add(int u, int v)
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{
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edge[num].u = u;
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edge[num].v = v;
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edge[num].next = head[u];
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head[u] = num++;
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}
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void init()
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{
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num = 0;
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memset(head, -1, sizeof(head));
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int u, v;
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for(int i=0; i<m; i++)
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{
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scanf("%d%d", &u, &v);
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add(u, v);
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add(v, u);
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}
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}
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int tarjan(int u)
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{
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lp[u] = low[u] = ++step;
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int tp = 0,v, cc=1;
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bool flag = 0;
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for(int i = head[u];i != -1;i = edge[i].next)
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{
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v = edge[i].v;
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if(v == f) continue;
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if(!lp[v])
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{
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cc++;
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tp++;
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tarjan(v);
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low[u] = min(low[u],low[v]);
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if(u != root&&lp[u] <= low[v])
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flag = 1;
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}
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else low[u] = min(low[u],lp[v]);
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}
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if(u == root && tp > 1)
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flag = 1;
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if(flag) ans++;
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return cc;
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}
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void solve()
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{
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int result = 0;
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int now, path[N] = {0};
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for(int i=1; i<=n; i++)
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{
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memset(low, 0, sizeof(low));
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memset(lp, 0, sizeof(lp));
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step = 1;
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now = ans = 0;
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f = i;
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for(int j=1; j<=n; j++)
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{
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if(!lp[j] && j!=i)
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{
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root = j;
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path[++now] = tarjan(j);
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}
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}
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if(now > 2) result += n-1;
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else if(now == 2)
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{
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sort(path+1, path+3);
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if(path[1] == 1)
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{
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if(path[2] != 1)
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result += n-2;
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}
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else result += n-1;
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}
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else result += ans;
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}
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printf("%d\n", result/2);
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}
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int main()
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{
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int t=0;
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while(scanf("%d%d", &n, &m) != EOF)
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{
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if(n==0 && m==0)
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break;
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init();
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t++;
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printf("Case %d: ", t);
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solve();
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}
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return 0;
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}
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