【BZOJ1562】【jzyzOJ1730】【COGS409】NOI2009变换序列 二分图匹配

#include<cstring>
#include<cstdio>
#include<algorithm>
#include<iostream>
#include<vector>
using namespace std;
int n;
int dis[10005];
int lin[10005];
int ans[10005];
bool f[10005];
vector<int>a[10005];

int flag(int q,int p)
{
    return min(abs(q-p),n-abs(q-p));
}

bool dfs(int x)
{
    int l=a[x].size();
    for(int i=0;i<l;++i)
    {
        if(!f[a[x][i]])
        {
            f[a[x][i]]=1;
            if(lin[a[x][i]]==-1||dfs(lin[a[x][i]]))
            {
                lin[a[x][i]]=x;
                return true;
            }
        }
    }
    return false;
}

int main()
{
    //freopen("a.txt","r",stdin);
    //freopen("b.txt","w",stdout);
    //freopen("transform.in","r",stdin);
    //freopen("transform.out","w",stdout);
    memset(a,0,sizeof(a));
    cin>>n;
    for(int i=0;i<n;++i)
        scanf("%d",&dis[i]);
    for(int i=0;i<n;++i)
    {
        int x=i+dis[i];
        int y=i+n-dis[i];
        x%=n;y%=n;
        if(flag(x,i)!=dis[i]) x=-1;
        if(flag(y,i)!=dis[i]) y=-1;
        if(x>y) swap(x,y);
        if(x!=-1) a[i].push_back(x);
        if(y!=-1) a[i].push_back(y);
    }
    
    memset(lin,-1,sizeof(lin));
    for(int i=n-1;i>=0;--i)
    {
        memset(f,0,sizeof(f));
        if(!dfs(i))
        {    
            cout<<"No Answer"<<endl;
            return 0;
        }
    }
    
    //cout<<123456<<endl;
    for(int i=0;i<n;++i)
        ans[lin[i]]=i;
    for(int i=0;i<n-1;++i)
        printf("%d ",ans[i]);
    cout<<ans[n-1]<<endl;
    return 0;
}