public int calculateMinimumHP(int[][] dungeon) {

int m = dungeon.length;

int 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);

//initializing the boundary.

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

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

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

for (int i = m-1; i >= 0; i--) {

for (int j = n-1; j >= 0; j--) {

int minPower = Math.min(dp[i+1][j], dp[i][j+1]) - dungeon[i][j];

// too much power already

dp[i][j] = (minPower <= 0) ? 1 : minPower;

}

}

return dp[0][0];

}

}