谜题

穷举一个数组中各个元素的排列

策略

减而治之、递归

JavaScript解

function getPermutation(arr) {
  if (arr.length == 1) {
    return [arr];
  }

  var permutation = [];
  for (var i=0; i<arr.length; i++) {
    var firstEle = arr[i];
    var arrClone = arr.slice(0);
    arrClone.splice(i, 1);
    var childPermutation = getPermutation(arrClone);
    for (var j=0; j<childPermutation.length; j++) {
      childPermutation[j].unshift(firstEle);
    }
    permutation = permutation.concat(childPermutation);
  }
  return permutation;
}

var permutation = getPermutation([\'a\',\'b\',\'c\']);
console.dir(permutation);