LeetCode（Array) 1672. Richest Customer Wealth

1.问题

You are given an m x n integer grid accounts where accounts[i][j] is the amount of money the ith customer has in the jth bank. Return the wealth that the richest customer has.

A customer’s wealth is the amount of money they have in all their bank accounts. The richest customer is the customer that has the maximum wealth.

Example 1:

Input: accounts = [[1,2,3],[3,2,1]]
Output: 6
Explanation:
1st customer has wealth = 1 + 2 + 3 = 6
2nd customer has wealth = 3 + 2 + 1 = 6
Both customers are considered the richest with a wealth of 6 each, so return 6.

Example 2:

Input: accounts = [[1,5],[7,3],[3,5]]
Output: 10
Explanation:
1st customer has wealth = 6
2nd customer has wealth = 10
3rd customer has wealth = 8
The 2nd customer is the richest with a wealth of 10.

Example 3:

Input: accounts = [[2,8,7],[7,1,3],[1,9,5]]
Output: 17

Constraints:

m == accounts.length
n == accounts[i].length
1 <= m, n <= 50
1 <= accounts[i][j] <= 100

2. 解题思路

方法1：

1.定义max初始值为0
2.遍历数组行的长度
3.遍历数组的列，将数组内的值相加
4.比较sum和max的最大值，取最大值作为max
5.返回max

方法2：

解题思路和方法1基本相同，不同的是使用Arrays.stream(customer).sum()方法，将数组中的所有值遍历再相加

3. 代码

代码1：

class Solution {
    public int maximumWealth(int[][] accounts) {
        int max =0;//1.定义max初始值为0   
        for (int i = 0; i < accounts.length; i++) {
    //2.遍历数组行的长度
             int sum=0;//定义变量sum为0
            for(int j =0;j<accounts[i].length;j++){
    //3.遍历数组的列，将数组内的值相加
                sum+=accounts[i][j];
            }
            max=Math.max(max,sum); //4.比较sum和max的最大值，取最大值作为max
            //if (sum > max) max = sum 如果不是用Math.max()方法，可以直接用if判断
        }
        return max;//5.返回max
    }
}

解题思路和以上基本相同，不同的在于使用for each遍历

class Solution {
    public int maximumWealth(int[][] accounts) {
        int max = 0;
        for(int[] account : accounts){
            int sum = 0;
            for(int s : account){
                sum = sum + s;
            }
            max = Math.max(max, sum);
        }
        return max;
    }
}

代码2：

class Solution {
    public int maximumWealth(int[][] accounts) {
        int maxWealth = 0;
        for (int[] customer : accounts){
    //解题思路基本相同，不同的是使用Arrays.stream(customer).sum()方法，将数组中的所有值遍历再相加
            maxWealth = Math.max(maxWealth, Arrays.stream(customer).sum());
        }
        return maxWealth;    
    }
}