P1006-传纸条

 1 #include <bits/stdc++.h>
 2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
 3 typedef long long ll;
 4 using namespace std;
 5 inline ll read()
 6 {
 7     ll ans = 0;
 8     char ch = getchar(), last = ' ';
 9     while(!isdigit(ch)) last = ch, ch = getchar();
10     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
11     if(last == '-') ans = -ans;
12     return ans;
13 }
14 inline void write(ll x)
15 {
16     if(x < 0) x = -x, putchar('-');
17     if(x >= 10) write(x / 10);
18     putchar(x % 10 + '0');
19 }
20 int n,m;
21 int a[52][52];
22 int dp[52][52][52][52];
23 int MightyMaXXX(int a,int b,int c,int d)
24 {
25     if(a<b) a=b;
26     if(a<c) a=c;
27     if(a<d) a=d;
28     return a;
29 } 
30 int main()
31 {
32     cin >> n >> m;
33     _for(i,1,n+1)
34         _for(j,1,m+1)
35             cin >> a[i][j];
36     
37     _for(i,1,n+1)
38         _for(j,1,m+1)
39             _for(k,1,n+1)
40                 _for(p,j+1,m+1)
41                     dp[i][j][k][p] = MightyMaXXX(dp[i-1][j][k-1][p],dp[i][j-1][k-1][p],dp[i-1][j][k][p-1],dp[i][j-1][k][p-1])+a[i][j]+a[k][p];
42     
43     printf("%d\n",dp[n][m-1][n-1][m]);
44     return 0;
45 }