[leetcode #1672] Richest Customer Wealth

Problem

You are given an m x n integer grid accounts where accounts[i][j] is the amount of money the i​​​​​​​​​​​th​​​​ customer has in the j​​​​​​​​​​​th​​​​ 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

Idea

사람들의 계좌가 주어지고, 각 계좌에 들어있는 예금 또한 주어진다. 이 때 가장 많은 예금을 가지고 있는 사람을 찾아, 그 계좌에 들어있는 돈의 합계를 구하라는 문제다.

모든 계좌를 뒤져 합을 구하고 가장 큰 합을 리턴하기만 하면 된다. (O(mn), m = 사람 수, n = 계좌 수)

Solution

class Solution {
    public int maximumWealth(int[][] accounts) {
        int res = 0;
        for (int[] customer : accounts) {
            int sum = 0;
            for (int money : customer) {
                sum += money;
            }
            res = Math.max(res, sum);
        }

        return res;
    }
}

Reference

https://leetcode.com/problems/richest-customer-wealth/