cf984e Elevator

ref我好菜啊

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
int n, u[2005], v[2005], f[2005][11][11][11][11];
int dis(int x, int y){
    return abs(x-y);
}
int dfs(int i, int cur, int a, int b, int c){
    if(f[i][cur][a][b][c]!=-1)  return f[i][cur][a][b][c];
    int re = 0x3f3f3f3f;
    if(i>n){
        if(!a && !b && !c)  return 0;
        if(a)   re = min(re, dfs(i, a, 0, b, c)+dis(cur,a)+1);
        if(b)   re = min(re, dfs(i, b, a, 0, c)+dis(cur,b)+1);
        if(c)   re = min(re, dfs(i, c, a, b, 0)+dis(cur,c)+1);
        f[i][cur][a][b][c] = re;
        return re;
    }
    if(a)   re = min(re, dfs(i, a, 0, b, c)+dis(cur,a)+1);
    if(b)   re = min(re, dfs(i, b, a, 0, c)+dis(cur,b)+1);
    if(c)   re = min(re, dfs(i, c, a, b, 0)+dis(cur,c)+1);
    if(a && b && c){
        re = min(re, dfs(i+1, v[i], a, b, c)+dis(cur,u[i])+dis(u[i],v[i])+2);
        re = min(re, dfs(i+1, a, v[i], b, c)+dis(cur,u[i])+dis(u[i],a)+2);
        re = min(re, dfs(i+1, b, a, v[i], c)+dis(cur,u[i])+dis(u[i],b)+2);
        re = min(re, dfs(i+1, c, a, b, v[i])+dis(cur,u[i])+dis(u[i],c)+2);
    }
    else{
        if(!a)  re = min(re, dfs(i+1, u[i], v[i], b, c)+dis(cur,u[i])+1);
        else if(!b) re = min(re, dfs(i+1, u[i], a, v[i], c)+dis(cur,u[i])+1);
        else    re = min(re, dfs(i+1, u[i], a, b, v[i])+dis(cur,u[i])+1);
    }
    f[i][cur][a][b][c] = re;
    return re;
}
int main(){
    cin>>n;
    for(int i=1; i<=n; i++)
        scanf("%d %d", &u[i], &v[i]);
    memset(f, -1, sizeof(f));
    cout<<dfs(1, 1, 0, 0, 0)<<endl;
    return 0;
}