代码如下
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 510, INF = 1e9;
int n;
int a[N][N];
int f[N][N];
int main()
{
cin >> n;
for (int i = 1; i <= n; i++ )
for (int j = 1; j <= i; j ++)
cin >> a[i][j];
for (int i = 0; i <= n; i++ )
for (int j = 0; j <= i + 1; j++)
f[i][j] = -INF;
f[1][1] = a[1][1];
//注意i从2开始
for (int i = 2; i <= n; i++)
for (int j = 1; j <= i; j ++ )
f[i][j] = max(f[i - 1][j - 1] + a[i][j], f[i - 1][j] + a[i][j]);
int res = -INF;
for (int i = 1; i <= n; i ++ ) res = max(res, f[n][i]);
printf("%d", res);
return 0;
}