luogu 1063

环形dp模板
开个二倍数组然后做区间dp

#include <cstdio>#include <algorithm>#include <cstring>#define MAXN 210using namespace std;int n, a[MAXN], f[MAXN][MAXN], ans;int read() {    int f = 1, k = 0;    char c = getchar();    while(c < '0' || c> '9') {        if(c == '-') {            f = -1;        }        c = getchar();    }    while(c >= '0' && c <= '9') {        k = k * 10 + c - '0';        c = getchar();    }    return f * k;}int main() {    n = read();    for(int i = 1; i <= n; i ++) {        a[i] = read();        a[i + n] = a[i];    }    for(int i = 2; i < 2 * n; i ++) {        for(int j = i - 1; j > 0 && i - j < n; j --) {            for(int k = j; k < i; k ++) {                f[j][i] = max(f[j][i], f[j][k] + f[k + 1][i] + a[j] * a[k + 1] * a[i + 1]);            }            ans = max(ans, f[j][i]);        }    }    printf("%d", ans);    return 0;}