class Solution
{
public:
    int calculateMinimumHP(vector<vector<int>> &dungeon)
    {
        if (dungeon.empty())
        {
            return 0;
        }
        int m = dungeon.size(), n = dungeon[0].size();
        vector<vector<long long>> dp(m + 1, vector<long long>(n + 1, INT_MAX));
        dp[m - 1][n] = dp[m][n - 1] = 1;
        for (int i = m - 1; i >= 0; --i)
        {
            for (int j = n - 1; j >= 0; --j)
            {
                dp[i][j] = min(dp[i + 1][j], dp[i][j + 1]) - dungeon[i][j];
                if (dp[i][j] <= 0)
                {
                    dp[i][j] = 1;
                }
            }
        }
        return dp[0][0];
    }
};