add 1380

Author: fishercoder1534

README.md

@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1380|[Lucky Numbers in a Matrix](https://leetcode.com/problems/lucky-numbers-in-a-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1380.java) | |Easy|Array|
 |1379|[Find a Corresponding Node of a Binary Tree in a Clone of That Tree](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1379.java) | |Medium|Tree|
 |1377|[Frog Position After T Seconds](https://leetcode.com/problems/frog-position-after-t-seconds/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1377.java) | |Hard|DFS, BFS|
 |1376|[Time Needed to Inform All Employees](https://leetcode.com/problems/time-needed-to-inform-all-employees/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1376.java) | |Medium|DFS|

src/main/java/com/fishercoder/solutions/_1380.java

@@ -0,0 +1,67 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 1380. Lucky Numbers in a Matrix
+ *
+ * Given a m * n matrix of distinct numbers, return all lucky numbers in the matrix in any order.
+ * A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.
+ *
+ * Example 1:
+ * Input: matrix = [[3,7,8],[9,11,13],[15,16,17]]
+ * Output: [15]
+ * Explanation: 15 is the only lucky number since it is the minimum in its row and the maximum in its column
+ *
+ * Example 2:
+ * Input: matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
+ * Output: [12]
+ * Explanation: 12 is the only lucky number since it is the minimum in its row and the maximum in its column.
+ *
+ * Example 3:
+ * Input: matrix = [[7,8],[1,2]]
+ * Output: [7]
+ *
+ * Constraints:
+ * m == mat.length
+ * n == mat[i].length
+ * 1 <= n, m <= 50
+ * 1 <= matrix[i][j] <= 10^5.
+ * All elements in the matrix are distinct.
+ * */
+public class _1380 {
+    public static class Solution1 {
+        public List<Integer> luckyNumbers(int[][] matrix) {
+            List<Integer> result = new ArrayList<>();
+            for (int i = 0; i < matrix.length; i++) {
+                for (int j = 0; j < matrix[0].length; j++) {
+                    if (luckyInRow(matrix[i][j], matrix[i])) {
+                        if (luckyInColumn(matrix[i][j], matrix, j)) {
+                            result.add(matrix[i][j]);
+                        }
+                    }
+                }
+            }
+            return result;
+        }
+
+        private boolean luckyInColumn(int number, int[][] matrix, int columnIndex) {
+            for (int i = 0; i < matrix.length; i++) {
+                if (number < matrix[i][columnIndex]) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        private boolean luckyInRow(int number, int[] row) {
+            for (int num : row) {
+                if (number > num) {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+}

src/test/java/com/fishercoder/_1380Test.java

@@ -0,0 +1,30 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1380;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1380Test {
+    private static _1380.Solution1 solution1;
+    private static int[][] matrix;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1380.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        matrix = new int[][]{
+                {3, 7, 8},
+                {9, 11, 13},
+                {15, 16, 17}
+        };
+        assertEquals(Arrays.asList(15), solution1.luckyNumbers(matrix));
+    }
+
+}