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原题链接：

https://vjudge.net/problem/UVA-1609


分类：构造法

备注：思维题

#include<bits/stdc++.h>
using namespace std;
const int maxn=1050;
char g[maxn][maxn];
int vis[maxn],out[maxn],len;
void dfs(int n){
    if(n==1)return;
    memset(vis,0,sizeof(vis));
    for(int i=2;i<=len;i++){
        if(out[i]||vis[i])continue;
        if(g[1][i]=='0'){
            for(int j=2;j<=len;j++){
                if(out[j]||vis[j])continue;
                if(g[1][j]=='1'&&g[j][i]=='1'){
                    vis[i]=vis[j]=1;
                    out[i]=1;
                    printf("%d %d\n",i,j);
                    break;
                }
            }
        }
    }
    for(int i=2;i<=len;i++){
        if(out[i]||vis[i])continue;
        if(g[1][i]=='1'){    
            printf("1 %d\n",i);
            vis[i]=1;
            out[i]=1;
            break;
        }
    }
    int flg=0,pre=0;
    for(int i=2;i<=len;i++){
        if(out[i]||vis[i])continue;
        if(g[1][i]=='0'){
            if(!flg){
                flg=1; pre=i;
            }else{
                flg=0;
                vis[pre]=vis[i]=1;
                printf("%d %d\n",pre,i);
                if(g[pre][i]=='0')out[pre]=1;
                else out[i]=1;
            }
        }
    }
    flg=0;
    for(int i=2;i<=len;i++){
        if(out[i]||vis[i])continue;
        if(!flg){
            flg=1; pre=i;
        }else{
            flg=0;
            vis[pre]=vis[i]=1;
            printf("%d %d\n",pre,i);
            if(g[pre][i]=='0')out[pre]=1;
            else out[i]=1;
        }
    }
    dfs(n>>1);
}
int main(void){
    //freopen("in.txt","r",stdin);
    while(~scanf("%d",&len)){
        for(int i=1;i<=len;i++)
            scanf("%s",g[i]+1);
        memset(out,0,sizeof(out));
        dfs(len);
    }
    return 0;
}