38 lines
1.1 KiB
C++
38 lines
1.1 KiB
C++
#include <bits/stdc++.h>
|
||
using namespace std;
|
||
typedef long long LL;
|
||
const int N = 1010;
|
||
const LL INF = 1e18;
|
||
|
||
LL f[N][N][3];
|
||
LL a[N][N];
|
||
int n, m;
|
||
|
||
int main() {
|
||
cin >> n >> m;
|
||
for (int i = 1; i <= n; i++)
|
||
for (int j = 1; j <= m; j++) {
|
||
cin >> a[i][j];
|
||
f[i][j][0] = f[i][j][1] = f[i][j][2] = -INF;
|
||
}
|
||
|
||
// 初始化
|
||
f[1][1][0] = f[1][1][1] = a[1][1];
|
||
for (int i = 2; i <= n; i++) f[i][1][1] = f[i - 1][1][1] + a[i][1];
|
||
|
||
for (int j = 2; j <= m; j++) {
|
||
for (int i = 1; i <= n; i++)
|
||
f[i][j][0] = max({f[i][j - 1][1], f[i][j - 1][0], f[i][j - 1][2]}) + a[i][j];
|
||
|
||
for (int i = 2; i <= n; i++)
|
||
f[i][j][1] = max(f[i - 1][j][0], f[i - 1][j][1]) + a[i][j];
|
||
|
||
for (int i = n - 1; i >= 1; i--)
|
||
f[i][j][2] = max(f[i + 1][j][0], f[i + 1][j][2]) + a[i][j];
|
||
}
|
||
|
||
cout << max(f[n][m][0], f[n][m][1]);
|
||
|
||
// 1e3 * 1e3 * 1e4=1e10=10000000000>2147483647 因为 1e10是11位数，INT_MAX是10位数,肯定会超，要开long long
|
||
return 0;
|
||
} |