code challenge

jsbin.xogizi.js

/*
Find all unique triplets in the array which gives the sum of 0.
a + b + c = 0;

[-1, 0, 1, 2, -1, -4]  ==> [[-1, 0, 1], [-1, -1, 2]];

*/

var temp = [-1, 0, 1, 2, -1, -4];

//a + b + c = 0; >>> a + b = -c; となる組み合わせを探す

var triplets = function(num) {
  var len = num.length,
      result = [];

  num.sort();
  
  for (var i = 0; i < len; i++) {
    //var target = 0 - num[i];
    var target = -1 * num[i];
    var start = i+1, end = len-1;
    
    while (start < end) {
      if (num[start] + num[end] == target) {
        var solution = [];
        solution.push([num[i], num[start], num[end]]);
        result.push(solution);
        start++;
        end--;
        while(start<end && num[start] == num[start-1])
           start++;
        while(start<end && num[end] == num[end+1])
          end--;
      } else if (num[start] + num[end] < target){
         start++;
      } else {
        end--;
      }    
    }
    if (i < len-1) {
      while(num[i] == num[i+1])
        i++;
    }
  }
  return result;
};

console.log(triplets(temp));