L1005矩阵取数游戏

 #include <bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 #define rep(i, a, b) for (ll i = a; i <= b; ++i)
 ;

 ll n, m, a[N], f[N][N], ans;

 int main() {
     scanf("%lld%lld", &n, &m);

     while (n--) {
         memset(f, , sizeof(f));
         rep(i, , m) {
             scanf("%lld", &a[i]);
             f[i][i] = a[i] * ( << m);
         }
         rep(len, , m) rep(i, , m - len + ) { ll j = i + len - ;
             f[i][j] = max(f[i][j], max(f[i][j - ] + a[j] * ( << (m +  - len)), f[i + ][j] + a[i] * ( << (m +  - len))));
         }
         ans += f[][m];
     }
     printf("%lld\n", ans);
     ;
 }

Tips：1.long long2.1 << (m + 1 - len)内外的顺序