5248: [2018多省省队联测]一双木棋

5248: [2018多省省队联测]一双木棋

链接

分析：

　　极大极小搜索！记忆化一下，所有的状态是阶梯状的！然后缩成一个LL。

　　好像状压dp也行。

　　考试的时候。。。啥都不会。。。不会极大极小搜索，不会dp，不会这道题！

代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;

inline int read() {
    int x=0,f=1;char ch=getchar();for(;!isdigit(ch);ch=getchar())if(ch=='-')f=-1;
    for (;isdigit(ch);ch=getchar())x=x*10+ch-'0';return x*f;
}

const int N = 20;
const LL base = 11;
int a[N][N],b[N][N],sta[N],n,m;
map<LL,int> p;

inline LL getHash() {
    LL ret = 0;
    for (int i=1; i<=n; ++i) ret = ret * base + sta[i];
    return ret;
}
inline void getState(LL S) {
    for (int i=n; i>=1; --i) sta[i] = S % base,S /= base;
}
int Minimax(int player,LL S) {
    if (p.find(S) != p.end()) return p[S];
    getState(S);
    int res = player ? 1e9 : -1e9;
    for (int i=1; i<=n; ++i) {
        if (sta[i-1] > sta[i]) {
            ++ sta[i];
            LL T = getHash();
            if (!player) res = max(res,Minimax(player^1,T) + a[i][sta[i]]) ;
            else res = min(res,Minimax(player^1,T) - b[i][sta[i]]) ;
            -- sta[i];
        }
    }
    p[S] = res;
    return res;
}

int main() {
    n = read(),m = read();
    for (int i=1; i<=n; ++i) 
        for (int j=1; j<=m; ++j) a[i][j] = read();
    for (int i=1; i<=n; ++i) 
        for (int j=1; j<=m; ++j) b[i][j] = read();
    
    for (int i=1; i<=n; ++i) sta[i] = m;
    p[getHash()] = 0;
    
    sta[0] = m;
    
    cout << Minimax(0,0);
    
    return 0;
}