174. Dungeon Game

class Solution {
    public int calculateMinimumHP(int[][] dungeon) {
        int m = dungeon.length, n = dungeon[0].length;
        int[][] dp = new int[m + 1][n + 1];
        for (int i = 0; i <= m; i++) {
            Arrays.fill(dp[i], Integer.MAX_VALUE);
        }

        dp[m][n - 1] = 1;
        dp[m - 1][n] = 1;

        for (int i = m - 1; i >= 0; i--) {
            for (int j = n - 1; j >= 0; j--) {
                int minHp = Math.min(dp[i + 1][j],
                   dp[i][j + 1]) - dungeon[i][j];

                if (minHp < 1) {
                    dp[i][j] = 1;
                } else dp[i][j] = minHp;
            }
        }

        return dp[0][0];
    }
}