feat: add Number of Laser Beams in a Bank (#1174)

Co-authored-by: David Leal <halfpacho@gmail.com>

leetcode/DIRECTORY.md

@@ -115,6 +115,7 @@
 | 1704 | [Determine if String Halves Are Alike](Determine if String Halves Are Alike)                                                    | [C](./src/1704.c) | Easy       |
 | 1752 | [Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/)                     | [C](./src/1752.c) | Easy       |
 | 2024 | [Maximize the Confusion of an Exam](https://leetcode.com/problems/maximize-the-confusion-of-an-exam/)                           | [C](./src/2024.c) | Medium     |
+| 2125 | [Number of Laser Beams in a Bank](https://leetcode.com/problems/number-of-laser-beams-in-a-bank/description/)                   | [C](./src/2125.c) | Medium     |
 | 2130 | [Maximum Twin Sum of a Linked List](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list/)                           | [C](./src/2130.c) | Medium     |
 | 2222 | [Number of Ways to Select Buildings](https://leetcode.com/problems/number-of-ways-to-select-buildings/)                         | [C](./src/2222.c) | Medium     |
 | 2256 | [Minimum Average Difference](https://leetcode.com/problems/minimum-average-difference/)                                         | [C](./src/2256.c) | Medium     |

leetcode/src/2125.c

@@ -0,0 +1,30 @@
+int coundDevices(char* bankRow){
+    int result = 0;
+    int bankRowSize = strlen(bankRow);
+    for(int i = 0; i < bankRowSize; i++){
+        if (bankRow[i] == '1'){
+            result++;
+        }
+    }
+
+    return result;
+}
+
+// Counting devices in each row
+// Runtime: O(n*m), n-number of bank rows, m - max size of row.
+// Space: O(1)
+int numberOfBeams(char ** bank, int bankSize){
+    int prevRowDevices = 0;
+    int result = 0;
+    for(int i = 0; i < bankSize; i++){
+        int devices = coundDevices(bank[i]);
+        if (devices == 0){
+            continue;
+        }
+
+        result += devices * prevRowDevices;
+        prevRowDevices = devices;
+    }
+
+    return result;
+}