前端笔记

排序算法

2018-05-15  本文已影响15人  好奇男孩

字典排序

let dict = {f: 3, b:1, c:2,a:{c:1,b:3,a:6}};
for (let key of Object.keys(dict).sort()) {
  console.log(key, dict[key]);
}

冒泡排序

     var bubbleSort = function (arr) {
        var length = arr.length;
        for(var i=0;i<length;i++){
            for (var j= 0;j<length-1-i;j++){
                if(arr[j] >arr[j+1]){
                    var aux =arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1]= aux;
                }
            }
        }
         return arr;
    };
    var arr1=[3,1,2,6,8,9,3,4,14,11,"a","h","c","b"];
    console.log(arr1);
    console.log(bubbleSort(arr1));

选择排序

    var selectionSort = function (arr) {
        var length = arr.length,indexMin;
        for (var i=0;i<length-1;i++){
            indexMin =i;
            for (var j=i;j<length;j++){
                if(arr[indexMin]>arr[j]){
                    indexMin = j;
                }
            }
            if(i !==indexMin){
                var aux =arr[i];
                arr[i] = arr[indexMin];
                arr[indexMin]= aux;
            }
        }
        return arr;
    }
var arr2=[3,1,2,6,8,9,3,4,14,11,"a","h","c","b"];
  console.log(selectionSort(arr2));

插入排序

    var insertionSort = function(arr){
        var len = arr.length;
        var j,temp;
        for( var i=1;i<len;i++){
            j=i;
            temp =arr[i];
            while(j> 0 && arr[j-1]>temp){
                arr[j]=arr[j-1];
                j--;
            }
            arr[j]=temp;
        }
        return arr;
    }
var arr3=[3,1,2,6,8,9,3,4,14,11,"a","h","c","b"];
console.log(insertionSort(arr3));

归并排序

function merge(left, right) {
    var tmp = [];
    while (left.length && right.length) {
        if (left[0] < right[0])
            tmp.push(left.shift());
        else
            tmp.push(right.shift());
    }
    return tmp.concat(left, right);
}
function mergeSort(a) {
    if (a.length === 1)
        return a;
    var mid = Math.floor(a.length / 2)
            , left = a.slice(0, mid)
            , right = a.slice(mid);
    console.log(left);
    console.log(right);
    return merge(mergeSort(left), mergeSort(right));
}
var arr4=[3,1,2,6,8,9,3,4,14,11,"a","h","c","b"];
console.log(mergeSort(arr4));

快速排序

    function quickSort(a) {
        if (a.length <= 1) return a;
        var mid = Math.floor(a.length / 2)
                , midItem = a.splice(mid, 1)[0]
                , left = []
                , right = [];
        a.forEach(function(item) {
            if (item <= midItem)
                left.push(item);
            else
                right.push(item);
        });
        var _left = quickSort(left),
            _right = quickSort(right);
        console.log(_left)
        console.log(_right)
        return _left.concat(midItem, _right);
    }
var arr5 = [6,8,9,3,"a",11,"h",3,"c"];
console.log(quickSort(arr5))

数组内置方法

console.log(arr5.sort(function(v1,v2){
    return v1 > v2;
}))
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