search_in_array.js

/**
 * Finds all number pairs in given array whose sum equals to 10
 * @param {Array} inputArray Array for search in
 * @returns {Array} Resulting array of number pairs
 */
function findInArray (inputArray) {

  var results = [];

  if (inputArray && inputArray.length) {
    // transform any custom array to flat one
    var flatArray = inputArray.toString().split(",");
    for (var i = 0; i < flatArray.length; i++) {
      var number1 = parseInt(flatArray[i]);
      for (var j = 0; j < flatArray.length; j++) {
        if (j === i) { continue; }
        var number2 = parseInt(flatArray[j]);
        if (number1 + number2 === 10) {
          results.push([number1, number2]);
        }
      }
    }
  }

  return results;
}


/**
 * Usage
 */
var testArray1 = [1, 2, 3, 4, 5, 6, 7, 8, 9];
var testArray2 = [[1, 2, 3], 4, [5, 6], [[7, 8], 9]];

console.log(findInArray(testArray1)); // [ [1,9], [2,8], [3,7], [4,6], [6,4], [7,3], [8,2], [9,1] ]
console.log(findInArray(testArray2)); // [ [1,9], [2,8], [3,7], [4,6], [6,4], [7,3], [8,2], [9,1] ]