Luogu1880 [NOI1995]石子合并 （区间DP）

一个1A主席树的男人，沦落到褪水DP举步维艰

#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <cmath>

#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)

#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)

#define Max(a,b) ((a) > (b) ? (a) : (b))

#define Min(a,b) ((a) < (b) ? (a) : (b))

#define Fill(a,b) memset(a, b, sizeof(a))

#define Abs(a) ((a) < 0 ? -(a) : (a))

#define Swap(a,b) a^=b^=a^=b

#define ll long long

//#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")

#define D_e(x)  cout << #x << " = " << x << endl

#define Pause() system("pause")

#define FileOpen() freopen("in.txt","r",stdin);

#else

#define D_e_Line ;

#define D_e(x)  ;

#define Pause() ;

#define FileOpen() ;

#endif

struct ios{

    template<typename ATP>ios& operator >> (ATP &x){

        x = 0; int f = 1; char c;

        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;

        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();

        x*= f;

        return *this;

    }

}io;

using namespace std;

const int N = 507;

int f_max[N][N], f_min[N][N], a[N], sum[N];

int main(){

	FileOpen();

	int n;

    io >> n;

    R(i,1,n){

    	io >> a[i];

    	a[i + n] = a[i];

    }

    R(i,1, n << 1) sum[i] = sum[i - 1] + a[i];

    R(len, 2, n){

        R(l, 1, n << 1){

            int r = l + len - 1;

            if(r > (n << 1)) continue;

            f_min[l][r] = 0x3f3f3f3f;

            R(k, l, r - 1){

                f_min[l][r] = Min(f_min[l][r], f_min[l][k] + f_min[k+1][r] + sum[r] - sum[l-1]);

                f_max[l][r] = Max(f_max[l][r], f_max[l][k] + f_max[k+1][r] + sum[r] - sum[l-1]);

            }

        }

    }

    int maxx = 0, minn = 0x7fffffff;

    R(i,1,n){

    	maxx = Max(maxx, f_max[i][i + n - 1]);

    	minn = Min(minn, f_min[i][i + n - 1]);

    }

    printf("%d\n%d", minn, maxx);

    return 0;

}

Luogu1880 [NOI1995]石子合并 （区间DP）的相关教程结束。