Cow Bowling POJ 3176 (basis dp)

The original title

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Topic analysis

Dp very basic problem, first original survive, and then making a match with the original dp, dp update scheme below, if j == 1 then the dp [i] [j] only from the layer dp [i-1] [j] to update over, therefore dp [i] [j] = dp [i-1] [j], if j == i, the dp [i] [j] only from the layer dp [i-1] [j-1] to update over, therefore dp [i] [j] = dp [i-1] [j-1], otherwise dp [i] [j] may be derived from dp [i-1] [j] may also be derived from dp [i-1] [j-1], therefore dp [i] [j] = max (dp [i-1] [j-1], dp [i-1] [j]).

Code

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <utility>
 4 #include <cstdio>
 5 #include <cmath>
 6 #include <cstring>
 7 #include <string>
 8 #include <vector>
 9 #include <stack>
10 #include <queue>
11 #include <map>
12 #include <set> 
13 
14 using namespace std;
15 typedef long long LL;
16 const int INF_INT=0x3f3f3f3f;
17 const LL INF_LL=0x3f3f3f3f3f3f3f3f;
18 
19 int dp[400][400];
20 int graph[400][400]; 
21 
22 int main()
23 {
24 //    freopen("black.in","r",stdin);
25 //    freopen("black.out","w",stdout);
26     int n;
27     cin>>n;
28     for(int i=1;i<=n;i++)
29     for(int j=1;j<=i;j++)
30     cin>>graph[i][j];
31     dp[1][1]=graph[1][1];
32     for(int i=2;i<=n;i++)
33     for(int j=1;j<=i;j++)
34     {
35         if(j==1) dp[i][j]=dp[i-1][j]+graph[i][j];
36         else if(j==i) dp[i][j]=dp[i-1][j-1]+graph[i][j];
37         else dp[i][j]=max(dp[i-1][j-1],dp[i-1][j])+graph[i][j];
38     }
39     int maxn=0;
40     for(int i=1;i<=n;i++) maxn=max(maxn,dp[n][i]);
41     cout<<maxn<<endl;
42     
43     return 0;
44 }