在狀態複雜,資訊多且資料小的情況下可以選擇考慮記憶化搜尋.這題我就做的很zz,一開始已知想打一個dp,
不過太麻煩了.看了解題報告之後才發現記憶化搜尋這麼簡單

#include<iostream>
#include<cstring>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fod(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
const int N=40+5,M=20+5; 
int dp[N][N][N][N],top[5],pile[5
 
][N],
n;
bool Hash[N];

void Init() {
    fo(i,0,n-1) fo(j,0,3) scanf("%d",&pile[j][i]);
    memset(dp,-1,sizeof(dp));
    memset(top,0,sizeof(top));
    memset(Hash,0,sizeof(Hash));
}

int dfs(int count, bool Hash[]) {
    if (dp[top[0]][top[1]][top[2]][top[3]] != -1)
        return dp[top[0]][top[1]][top[2
 
]][top[3]];

    if (count == 5) 
        return dp[top[0]][top[1]][top[2]][top[3]] = 0;

    int ans = 0;
    for (int i = 0; i < 4; i++) {
        if (top[i] == n) continue;
        int color = pile[i][top[i]];
        top[i] += 1;
        if (Hash[color]) {
            Hash[color] = false;
            ans = max(ans, dfs(count-1
 
, Hash) + 1);
            Hash[color] = true;
        } else {
            Hash[color] = true;
            ans = max(ans, dfs(count+1, Hash));
            Hash[color] = false;
        }
        top[i] -= 1;
    }
    return dp[top[0]][top[1]][top[2]][top[3]] = ans;
}

int main() {
    while(scanf("%d",&n)&&n) {
        Init();
        printf("%d\n",dfs(0,Hash));
    }
    return 0;   
}