[CF] 8C Looking for Order

Like platen title difficulty CF 2000? I'll have to look at the mechanism of the CF difficult

Anyway, the real difficulty CF is like the Los Valley

Code

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#define N 25
#define INF 0x3f3f3f3f
using namespace std;
inline int read() {
    int x=0,f=1; char ch=getchar();
    while(ch<'0' || ch>'9') { if(ch=='-') f=-1; ch=getchar(); }
    while(ch>='0'&&ch<='9') { x=(x<<3)+(x<<1)+(ch^48); ch=getchar(); }
    return x * f;
}
int n;
int x[N],y[N];
int g[N][N];
int f[1<<N],pre[1<<N];  //状压dp 
void print(int u) {
    printf("0 ");
    if(u == 0) return;
    int bit = u ^ pre[u];   //拿出这两个数 
    for(int i=1;i<=n;++i)
        if(bit & (1<<(i-1)))
            printf("%d ",i);
    print(pre[u]);
}
int main()
{
    x[0] = read(), y[0] = read(); n = read();
    for(int i=1;i<=n;++i)
        x[i] = read(), y[i] = read();
    memset(g, 0x3f, sizeof(g));
    for(int i=0;i<=n;++i)
        for(int j=0;j<=n;++j)
            g[i][j] = g[j][i] = (x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]);
    memset(f, 0x3f, sizeof(f));
    int maxn = (1<<n)-1;
    f[0] = 0;
    for(int S=0;S<=maxn;++S) {  //state
        if(f[S] == INF) continue;
        for(int i=1;i<=n;++i) {
            if(S & (1<<(i-1))) continue;
            for(int j=1;j<=n;++j) {
                if(S & (1<<(j-1))) continue;
                int x = S | (1<<(i-1)) | (1<<(j-1));
                int y = f[S] + g[0][i] + g[i][j] + g[j][0];
                if(y < f[x]) {
                    f[x] = y;
                    pre[x] = S;
                }
            }
            break;
        }
    }
    printf("%d\n",f[maxn]);
    print(maxn);
    return 0;
}