AtCoder Beginner Contest 147 E. Balanced Path

思路：

dp，使用了bitset优化。

实现：

 #include <bits/stdc++.h>
 using namespace std;
 const int N = ;
 const int INF = 0x3f3f3f3f;
 int a[N][N], b[N][N];
 bitset<N * N * > dp[N][N];

 int main()
 {
     int h, w;
     while (cin >> h >> w)
     {
         for (int i = ; i < h; i++)
         {
             for (int j = ; j < w; j++)
             {
                 cin >> a[i][j];
             }
         }
         for (int i = ; i < h; i++)
         {
             for (int j = ; j < w; j++)
             {
                 cin >> b[i][j];
             }
         }
         for (int i = ; i < h; i++)
         {
             for (int j = ; j < w; j++)
             {
                 dp[i][j].reset();
             }
         }
         dp[][][a[][] - b[][] + N * N * ] = ;
         dp[][][b[][] - a[][] + N * N * ] = ;
         for (int i = ; i < h; i++)
         {
             for (int j = ; j < w; j++)
             {
                 int tmp = abs(a[i][j] - b[i][j]);
                 if (j)
                 {
                     dp[i][j] |= dp[i][j - ] << tmp;
                     dp[i][j] |= dp[i][j - ] >> tmp;
                 }
                 if (i)
                 {
                     dp[i][j] |= dp[i - ][j] << tmp;
                     dp[i][j] |= dp[i - ][j] >> tmp;
                 }
             }
         }
         int res = INF;
         for (int i = ; i < N * N * ; i++)
         {
             if (dp[h - ][w - ][i]) res = min(res, abs(i - N * N * ));
         }
         cout << res << endl;
     }
     return ;
 }