174. Dungeon Game

从底往上，注意必须保证他有1滴血。

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

        int rows = dungeon.length;
        int cols = dungeon[0].length;
        if(rows == 0&&cols ==0)
            return 0;
        int[][]dp = new int[dungeon.length][dungeon[0].length];
        int max=-99999999;
        for(int i=rows-1;i>=0;i--){
            for(int j=cols-1;j>=0;j--){
                if(i==rows-1&&j==cols-1){

                    dp[i][j] = Math.max(1-dungeon[i][j],1);
                    continue;
                }
                if(j==cols-1){
                    dp[i][j] = Math.max(dp[i+1][j]-dungeon[i][j],1);

                }else if(i==rows-1){
                    dp[i][j] = Math.max(dp[i][j+1]-dungeon[i][j],1);
                }else{
                    int right = Math.max(dp[i][j+1]-dungeon[i][j],1);
                    int down = Math.max(dp[i+1][j]-dungeon[i][j],1);
                    dp[i][j] = Math.min(right,down);
                }
            }
        }
        if(dp[0][0]<=0)return 1;
        return dp[0][0];


    }
}