记录编号	593225	评测结果	AAAAAAAAAA
题目名称	4006.Partition	最终得分	100
用户昵称	┭┮﹏┭┮	是否通过	通过
代码语言	C++	运行时间	3.364 s
提交时间	2024-08-27 19:59:58	内存使用	102.99 MiB

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define fi first
#define in inline
#define se second
#define mp make_pair
#define pb push_back
const int N = 2e3+10;
const ll inf = 1e18;

ll read(){
	ll x = 0,f = 1;char c = getchar();
	for(;c < '0' || c > '9';c = getchar())if(c == '-')f = -1;
	for(;c >= '0' && c <= '9';c = getchar())x = (x<<1) + (x<<3) + c-'0';
	return x * f;
}


int n,m;
ll a[N][N],f[N][N],g[N][N],s[N][N],ans;
int main(){
	freopen("partition.in","r",stdin);
	freopen("partition.out","w",stdout);
	n = read(),m = read();
	for(int i = 1;i <= n;i++)
		for(int j = 1;j <= m;j++)a[i][j] = read(),ans += a[i][j];
	for(int i = n;i >= 1;i--)
		for(int j = 1;j <= m;j++)s[i][j] = s[i+1][j] + a[i][j];
	memset(f,-0x7f,sizeof f);
	memset(g,-0x7f,sizeof g);
	f[0][1] = g[0][m+1] = 0;
	for(int i = 0;i <= n+1;i++)f[i][1] = g[i][m+1] = 0;
	for(int i = 1;i <= n+1;i++){
		for(int j = 2;j <= m+1;j++)f[i][j] = max(f[i-1][j],f[i][j-1] + s[i][j-1]);
		for(int j = m;j >= 1;j--)g[i][j] = max(g[i-1][j],g[i][j+1] + s[i][j]);
	}
	printf("%lld\n",ans + 2ll * f[n+1][m+1] + g[n+1][1]);
 
	return 0;

}