added task #1672 solution and explanation of it

Author: nesterrovv

src/task_1672/README.md

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+# Intuition
+It seems easy. It's interesting to count sum of a row of given grid. It's a sum of money in all banks for one customer. Let's find maximum in set of "row-sums".
+
+# Approach
+Row sum is sum of money in all banks for one customer. Let's save this value to a ```moneyOfCurrentCustomer``` variable. After that, let's compare: is this value greater than ```moneyOfRichestCustomer``` value? If yes, let's re-write value of maximum. After that, it's necessary to save 0 to ```moneyOfCurrentCustomer``` variable (we are not calculating money sum for all people!) and repeat iteration.
+
+# Complexity
+- Time complexity:
+  $O(n*m)$, where $n$ is number of rows, $m$ is number of columns in the grid. Necessary to iterate by all rows and all columns for finding an answer.
+
+- Space complexity:
+  $O(1)$. There are only two ```int``` type variables for storing all necessary data.
+
+# Code
+```
+class Solution {
+
+    public int maximumWealth(int[][] accounts) {
+        int moneyOfRichestCustomer = 0;
+        int moneyOfCurrentCustomer = 0;
+        for (int i = 0; i < accounts.length; i++) {
+            for (int j = 0; j < accounts[i].length; j++) {
+                moneyOfCurrentCustomer += accounts[i][j];
+            }
+            if (moneyOfCurrentCustomer > moneyOfRichestCustomer) {
+                moneyOfRichestCustomer = moneyOfCurrentCustomer;
+            }
+            moneyOfCurrentCustomer = 0;
+        }
+        return moneyOfRichestCustomer;
+    }
+    
+}
+```

src/task_1672/Solution.java

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+package task_1672;
+
+import java.util.Arrays;
+
+/*
+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
+ */
+public class Solution {
+
+    public int maximumWealth(int[][] accounts) {
+        int moneyOfRichestCustomer = 0;
+        int moneyOfCurrentCustomer = 0;
+        for (int i = 0; i < accounts.length; i++) {
+            for (int j = 0; j < accounts[i].length; j++) {
+                moneyOfCurrentCustomer += accounts[i][j];
+            }
+            if (moneyOfCurrentCustomer > moneyOfRichestCustomer) {
+                moneyOfRichestCustomer = moneyOfCurrentCustomer;
+            }
+            moneyOfCurrentCustomer = 0;
+        }
+        return moneyOfRichestCustomer;
+    }
+
+}