BZOJ3895 取石子

Orz PoPoQQQ

我等蒟蒻只能想到石子数 ≥ 2时的情况。。。1的时候就爆搜？大概是这个意思

最后再记忆化一下

 /**************************************************************
     Problem: 3895
     User: rausen
     Language: C++
     Result: Accepted
     Time:500 ms
     Memory:12524 kb
 ****************************************************************/

 #include <cstdio>
 #include <cstring>

 using namespace std;

 int n;
 int f[][];

 int dfs(int a, int b) {
     if (!a) return b & ;
     if (b == ) return dfs(a + , );
     if (~f[a][b]) return f[a][b];
     if ((a && !dfs(a - , b)) || (a && b && !dfs(a - , b + )) || (a >=  && !dfs(a - , b +  + (b > ))) || (b && !dfs(a, b - ))) return f[a][b] = ;
     return f[a][b] = ;
 }

 int main() {
     int T, i, a, b, x;
     memset(f, -, sizeof(f));
     scanf("%d", &T);
     while (T--) {
         scanf("%d", &n);
         for (i = , a = , b = -; i <= n; ++i) {
             scanf("%d", &x);
             if (x == ) ++a;
             else b += x + ;
         }
         if (b == -) b = ;
         puts(dfs(a, b) ? "YES" : "NO");
     }
     return ;
 }