Luogu1063 能量项链 （区间DP）

惊恐地发现自己连区间DP都会错2333

#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 = 1007;

int a[N], f[N][N];

int main(){

	//FileOpen();

	int n;

    io >> n;

    R(i,1,n){

    	io >> a[i];

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

    }

    int ans = 0;

    R(len,2,n){

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

    		int r = l + len - 1;

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

    		R(k, l + 1, r){

    			f[l][r] = Max(f[l][r], f[l][k - 1] + f[k][r] + a[l] * a[k] * a[r + 1]);

    			ans = Max(ans, f[l][r]);

    		//1	printf("f %d %d :%d\n", l, r, f[l][r]);

    		}

    	}

    }

    printf("%d", ans);

	return 0;

}

Luogu1063 能量项链 （区间DP）的相关教程结束。