85 lines
1.8 KiB
C++
85 lines
1.8 KiB
C++
#pragma comment(linker, "/STACK:1024000000,1024000000")
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#include <stdio.h>
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#include <string.h>
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#include <iostream>
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#include <algorithm>
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#include <vector>
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#include <queue>
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#include <set>
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#include <map>
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#include <string>
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#include <math.h>
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#include <stdlib.h>
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#include <time.h>
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using namespace std;
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const int MAXN = 110;
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int color[MAXN];
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int head[MAXN];
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struct Edge
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{
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int to,next;
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}edge[MAXN*MAXN];
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int tot;
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void addedge(int u,int v)
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{
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edge[tot].to = v;
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edge[tot].next = head[u];
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head[u] = tot++;
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}
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void init()
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{
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tot = 0;
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memset(head,-1,sizeof(head));
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}
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bool dfs(int u,int col)
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{
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color[u] = col;
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for(int i = head[u];i != -1;i = edge[i].next)
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{
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int v = edge[i].to;
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if(color[v] != -1)
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{
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if(color[v]==col)return false;
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continue;
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}
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if(!dfs(v,!col))return false;
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}
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return true;
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}
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int g[MAXN][MAXN];
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int main()
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{
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int n;
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while(scanf("%d",&n) == 1)
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{
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memset(g,0,sizeof(g));
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int t;
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for(int i = 1;i <= n;i++)
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{
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while(scanf("%d",&t) && t)
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{
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g[i][t] = 1;
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}
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}
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init();
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for(int i = 1;i <= n;i++)
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for(int j = i+1;j <= n;j++)
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if(g[i][j] == 0 || g[j][i] == 0)
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{
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addedge(i,j);
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addedge(j,i);
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}
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memset(color,-1,sizeof(color));
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bool flag = true;
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for(int i = 1;i <= n;i++)
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if(color[i] == -1 && dfs(i,0) == false)
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{
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flag = false;
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break;
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}
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if(flag)printf("YES\n");
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else printf("NO\n");
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}
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return 0;
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}
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