HDU 2686 Matrix 多线程dp
题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=2686
思路:多线程dp,参考51Nod 1084:http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1084
注:这道题用滚动数组优化反而WA,压到三维即可
代码:
1 #include <bits/stdc++.h> 2 using namespace std; 3 int ans[30][30],dp[60][30][30]; 4 int main() { 5 int n; 6 while(~scanf("%d",&n)) { 7 for(int i=1;i<=n;++i) 8 for(int j=1;j<=n;++j) 9 scanf("%d",&ans[i][j]); 10 memset(dp,0,sizeof(dp)); 11 dp[0][1][1]=ans[1][1];//一步都没走 12 for(int tot=1;tot<=n+n-2;++tot)//走了几步 13 for(int i=1;i<=n&&(i-1<=tot);++i) 14 for(int j=1;j<=n&&(j-1<=tot);++j) { 15 dp[tot][i][j]=max(dp[tot][i][j],dp[tot-1][i-1][j-1]); 16 dp[tot][i][j]=max(dp[tot][i][j],dp[tot-1][i-1][j]); 17 dp[tot][i][j]=max(dp[tot][i][j],dp[tot-1][i][j-1]); 18 dp[tot][i][j]=max(dp[tot][i][j],dp[tot-1][i][j])+ans[i][tot+2-i]+ans[j][tot+2-j]; 19 if(i==j) dp[tot][i][j]-=ans[i][tot+2-i]; 20 } 21 printf("%d\n",dp[n+n-2][n][n]); 22 } 23 return 0; 24 }