JavaScript实现数组全排列、去重及求最大值算法示例

function permutation(arr){  if (arr.length == 1)    return arr;  else if (arr.length == 2)    return [[arr[0],arr[1]],[arr[1],arr[0]]];  else {    var temp = [];    for (var i = 0; i < arr.length; i++) {      var save = arr[i];      arr.splice(i, 1);//取出arr[i]      var res = permutation(arr);//递归排列arr[0],arr[1],...,arr[i-1],arr[i+1],...,arr[n]      arr.splice(i, 0, save);//将arr[j]放入数组，保持原来的位置      for (var j = 0; j < res.length; j++) {        res[j].push(arr[i]);        temp.push(res[j]);//将arr[j]组合起来      }    }    return temp;  }}

function norepeat(contents) {  var norepeatContents = [];  for (var i = 0; i < contents.length; i++) {    if(norepeatContents.indexOf(contents[i]) == -1)      norepeatContents.push(contents[i]);  }  return norepeatContents;}

function norepeat(contents) {  var norepeatContents = [], hash = {};  for (var i = 0; i < contents.length; i++) {    if(!hash[contents[i]]) {      norepeatContents.push(contents[i]);      hash[contents[i]] = true;    }  }  return norepeatContents;}

function findMax(arr) {  var max = arr[0];  for (var i = 1; i < arr.length; i++) {    if (arr[i] > max)      max = arr[i];  }  return max;}

function findMax(arr) {  return Math.max.apply(Math, arr);}