/* 题意:还是二进制异或,和poj3678类似 建边和poj3678一样 */ #include<stdio.h> #include<string.h> #include<math.h> #define N 2100 struct node { int v,next; } bian[N*N]; int head[N],dfn[N],low[N],vis[N],stac[N],belong[N],yong,ans,index,top; void init() { yong=index=ans=top=0; memset(head,-1,sizeof(head)); memset(vis,0,sizeof(vis)); memset(dfn,0,sizeof(dfn)); } void addedge(int u,int v) { bian[yong].v=v; bian[yong].next=head[u]; head[u]=yong++; } int Min(int v,int vv) { return v>vv?vv:v; } void tarjan(int u) { dfn[u]=low[u]=++index; stac[++top]=u; vis[u]=1; int i; for(i=head[u]; i!=-1; i=bian[i].next) { int v=bian[i].v; if(!dfn[v]) { tarjan(v); low[u]=Min(low[u],low[v]); } else if(vis[v]) low[u]=Min(low[u],dfn[v]); } if(dfn[u]==low[u]) { ++ans; int t; do { t=stac[top--]; belong[t]=ans; vis[t]=0; } while(t!=u); } } int ma[N][N]; int judge(int n) { int i,j; for(i=0; i<n; i++) { if(ma[i][i])return 1; for(j=0; j<n; j++) if(ma[i][j]!=ma[j][i])return 1; } return 0; } int endd(int n) { int i; for(i=0; i<2*n; i++)if(!dfn[i])tarjan(i); for(i=0; i<n; i++) if(belong[i]==belong[i+n]) return 1; return 0; } int main() { int n,m,i,j,k; while(scanf("%d",&n)!=EOF) { for(i=0; i<n; i++) for(j=0; j<n; j++) scanf("%d",&ma[i][j]); if(judge(n)) { printf("NO "); continue; } for(k=0; k<32; k++) { init(); for(i=0; i<n; i++) for(j=i+1; j<n; j++) { if(i==j)continue; m=ma[i][j]&(1<<k); if(i%2==1&&j%2==1) { if(m) { addedge(i+n,j); addedge(j+n,i);//0,0 } else { addedge(i,j); addedge(j+n,i+n);//1,0 addedge(i+n,j+n); addedge(j,i);//0,1 addedge(i,j+n); addedge(j,i+n);//1,1 } } else if(i%2==0&&j%2==0) { if(m) { addedge(i,j); addedge(j+n,i+n);//1,0 addedge(i+n,j+n); addedge(j,i);//0,1 addedge(i+n,j); addedge(j+n,i);//0,0 } else { addedge(i,j+n); addedge(j,i+n);//1,1 } } else { if(m) { addedge(i+n,j); addedge(j+n,i);//0,0 addedge(i,j+n); addedge(j,i+n);//1,1 } else { addedge(i,j); addedge(j+n,i+n);//1,0 addedge(i+n,j+n); addedge(j,i);//0,1 } } } if(endd(n))break; } if(k==32)printf("YES "); else printf("NO "); } return 0; }