二维DP，不知道怎么错的，求大佬帮忙看看

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

int v[250][250], f[250][250];

int main()
{
	int n, m;
	cin >> n;
	cin >> m;
    memset(v, -999999, sizeof(v));
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			cin >> v[i][j];
		}
	}
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			f[i][j] = max({f[i - 1][j], f[i - 1][j - 1], f[i - 1][j + 1]}) + v[i][j];
		}
	}
    cout << max({f[n][m], f[n][m / 2 + 1], f[n][m / 2 + 2]});
	return 0;
}