// integerPairs
// Design an algorithm to find all pairs of integers within an array which sum to a specified value.
// Input: array
// Output: array of pairs
// Time complexity: O(n)
// Space complexity: no constraints
// Example:
// Input: [3, 2, 8, 9, -1, 4, 5, 12, 1], 7
// Output: [ [ 3, 4 ], [ 2, 5 ], [ 8, -1 ] ] (order of pairs does not matter)

var input = [3, 2, 8, 9, -1, 4, 5, 12, 1] //7
var target = 7;

function integerPairs(input, target) {
  // make one array to hold all arrays
  var largeArray = [];
  // loop through the input array
  for(var i = 0; i < input.length; i++) {
    // crate a variable array to hold number pairs that sum to the target
    var smallArray = [];
    // make a 2nd loop to check the number next to the starting input value
    for(var j = i+1; j < input.length; j++) {
      // check to see if the two values sum to the target value
      if(input[i] + input[j] === target) {
        // if yes, push both values into the small array
        smallArray.push(input[i], input[j])
        // push the array of the pairs into a large array
        largeArray.push(smallArray);
      }
    }
  }
  // return the large array
  return largeArray;
}
integerPairs(input, target);