Finding Lucky Numbers in a Matrix in JavaScript

Lucky Number:

A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.

We are required to write a JavaScript function that takes in a two-dimensional array of integers.

The function should find all the lucky numbers in the array, construct a new array and return all the lucky number within that array.

For example −

If the input array is −

const arr = [
   [5, 3, 7, 3],
   [4, 2, 67, 2],
   [2, 32, 7, 4],
   [2, 9, 45, 23]
];

Then the output should be −

const output = [];

Example

Following is the code −

const arr = [
   [5, 3, 7, 3],
   [4, 2, 67, 2],
   [2, 32, 7, 4],
   [2, 9, 45, 23]
];
const luckyNumbers = (arr = []) => {
   const column = arr.length;
   for(let c = 0; c < column; c++){
      let minRow = Math.min(...arr[c]);
      let pos = arr[c].indexOf(minRow);
      if(minRow === arr[c][pos]){
         let tmpMaxColumn = arr[c][pos];
         for(let j = 0; j < column; j++){
            if(arr[j][pos] > tmpMaxColumn){
               tmpMaxColumn = arr[j][pos];
               break;
            }
         }
         if(tmpMaxColumn === minRow){
            return [tmpMaxColumn];
         }
      }
   };
   return [];
};
console.log(luckyNumbers(arr));

Output

Following is the console output −

[]