礼物的最大价值

经典dp问题

class Solution {
    public int maxValue(int[][] grid) {
    int m=grid.length,n=grid[0].length;
    for(int i=0;i<m;i++){
        for(int j=0;j<n;j++){
            if(i==0&&j>0){
                grid[i][j]=grid[i][j-1]+grid[i][j];
            }else if(j==0&&i>0){
                grid[i][j]=grid[i-1][j]+grid[i][j];
            }else if(i>0&&j>0){
                 grid[i][j]=Math.max(grid[i-1][j],grid[i][j-1])+grid[i][j];
            }
           
        }
    }
    return grid[m-1][n-1];
    }
}