牛客网 小白月赛G题 DP

//#include <bits/stdc++.h>
#include<stdio.h>
#include<string.h>
#include<string>
#include<math.h>
#include<algorithm>
#include<iostream>
#include<queue>
#include<vector>
#include<stac
4000
k>
#include<map>
#include<set>
#include<stdlib.h>
#include<time.h>
#include <iomanip>
#define lowbit(x) (x&(-x))
#define inf  0x7fffffff
#define linf 0x7fffffffffffffff
#define fill(x,y) memset(x,y,sizeof(x))
#define fup(i,x,y) for(int i=(x);i<=(y);i++)
#define fdn(i,x,y) for(int i=(x);i>=(y);i--)
#define sp(x) setprecision(x)
#define sd(n) scanf("%d",&n)
#define sdd(n,m) scanf("%d%d",&n,&m)
#define sddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define sld(n) scanf("%lld",&n)
#define sldd(n,m) scanf("%lld%lld",&n,&m)
#define slddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define sf(n) scanf("%lf",&n)
#define sff(n,m) scanf("%lf%lf",&n,&m)
#define sfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define sc(n) scanf("%s",n)
#define pf(x) printf("%d\n",x)
#define pfl(x) printf("%lld\n",x)
#define pff(x) printf("%lf\n",x)
#define N 1000005
#define M 4000009

#define pi acos(-1)
#define eps 1e-2
//cout.setf(ios::fixed);
//freopen("out.txt","w",stdout);// freopen("in.txt","r",stdin);
using namespace std;
typedef long long  ll;
typedef double db;
int vis[3200][2005],a[3200][2005];
int go[6][2]={1,-1,1,0,1,1,-1,1,-1,0,-1,-1};
void dfs(int x,int y,int n,int t)
{
if(!t) return ;
fup(i,0,n-1)
vis[x+2*i][y]=1;
dfs(x+1,y-1,n-1,t-1);
}
void dfs1(int x,int y,int n,int t)
{
if(!t) return ;
fup(i,0,n-1)
vis[x+2*i][y]=1;
dfs1(x+1,y+1,n-1,t-1);
}
int main()
{
int n;
while(~sd(n))
{
fill(vis,0);
fill(a,-0x3f3f3f3f);
vector<int> q[3200];
dfs(1,n,2*n-1,n);
dfs1(2,n+1,2*n-2,n-1);
//      fup(i,1,4*n-3)
//      {
//          fup(j,1,2*n-1)
//         cout<<vis[i][j]<<' ';
//          puts("");
//      }
fup(i,1,4*n-3)
{
fup(j,1,2*n-1)
if(vis[i][j]) sd(a[i][j]),q[i].push_back(j);
}
fdn(i,4*n-4,1)
{
int m=q[i].size();
for(int j=0;j<m;j++)
{
int tp=q[i][j];
a[i][tp]+=max(a[i+1][tp-1],max(a[i+2][tp],a[i+1][tp+1]));
}
}
pf(a[1]
);
}
return 0;
}