C++ 代码

#include<iostream>
#include<algorithm>
using namespace std;

const int N = 510,INF = 1e9;
int n;
int a[N][N],f[N][N];

int main()
{
    scanf("%d",&n);
    for(int i = 1;i <= n;i ++)
        for(int j = 1;j <= i;j ++)
            scanf("%d",&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];
    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\n",res);
    return 0;
}