feat: Add solution for lucky-numbers-in-a-matrix problem

Author: pragusga25

easy/lucky-numbers-in-a-matrix.test.ts

@@ -0,0 +1,80 @@
+const luckyNumbers = (matrix: number[][]): number[] => {
+  const [rows, cols] = [matrix.length, matrix[0].length];
+  const minRows: Record<number, [number, number]> = {};
+  const maxCols: Record<number, [number, number]> = {};
+
+  for (let row = 0; row < rows; row++) {
+    let minRowsVal: [number, number] = [10e5 + 1, -1];
+    for (let col = 0; col < cols; col++) {
+      const val = matrix[row][col];
+
+      if (val < minRowsVal[0]) {
+        minRowsVal = [val, col];
+      }
+
+      if (!(col in maxCols)) {
+        maxCols[col] = [val, row];
+      }
+
+      if (val > maxCols[col][0]) {
+        maxCols[col] = [val, row];
+      }
+    }
+
+    minRows[row] = minRowsVal;
+  }
+
+  const ans: number[] = [];
+
+  Object.entries(minRows).forEach(([row, [val, col]]) => {
+    const [_, rowVal] = maxCols[col];
+
+    if (rowVal === Number(row)) ans.push(val);
+  });
+
+  return ans;
+};
+
+describe('Lucky Numbers in a Matrix', () => {
+  it('#1 should return [15]', () => {
+    expect(
+      luckyNumbers([
+        [3, 7, 8],
+        [9, 11, 13],
+        [15, 16, 17],
+      ])
+    ).toEqual([15]);
+  });
+
+  it('#2 should return [12]', () => {
+    expect(
+      luckyNumbers([
+        [1, 10, 4, 2],
+        [9, 3, 8, 7],
+        [15, 16, 17, 12],
+      ])
+    ).toEqual([12]);
+  });
+
+  it('#3 should return [7]', () => {
+    expect(
+      luckyNumbers([
+        [7, 8],
+        [1, 2],
+      ])
+    ).toEqual([7]);
+  });
+
+  it('#4 should return [1]', () => {
+    expect(
+      luckyNumbers([
+        [1, 2],
+        [3, 4],
+      ])
+    ).toEqual([3]);
+  });
+
+  it('#5 should return [1]', () => {
+    expect(luckyNumbers([[1, 2, 3]])).toEqual([1]);
+  });
+});