hdu1545 dp[i][x][y]表示到i位，从i到之前1比0最多多x个，0比1最多多y个（注意边界）...

T^T老是把转移方程方向想错

 1 #include<stdio.h>
 2 #include<string.h>
 3 long long dp[75][15][15];
 4 int  main()
 5 {
 6     int n,k,i,j,x,y;
 7      long long sum;
 8     while (~scanf("%d%d",&n,&k))
 9     {
10         memset(dp,0,sizeof(dp));
11         dp[1][1][0]=dp[1][0][1]=1;
12         for (i=2;i<=n;i++)
13             for (x=0;x<=k;x++)
14                 for (y=0;y<=k;y++)
15         {
16             if (x==0&&y==0) continue;
17             if (x==0) dp[i][x][y]=dp[i-1][x][y-1]+dp[i-1][x+1][y-1];
18             else if (y==0) dp[i][x][y]=dp[i-1][x-1][y]+dp[i-1][x-1][y+1];
19             else dp[i][x][y]=dp[i-1][x-1][y+1]+dp[i-1][x+1][y-1];
20         }
21         sum=0;
22         for (i=0;i<=k;i++)
23             for (j=0;j<=k;j++)
24             if (i!=0||j!=0)
25             sum+=dp[n][i][j];
26         printf("%I64d\n",sum);
27     }
28 }

http://acm.hdu.edu.cn/showproblem.php?pid=1545

转载于:https://www.cnblogs.com/xiao-xin/articles/4063496.html