Wills's blogs

前端算法题

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js写冒泡排序

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function bubbleSort(arr){
  var arrLen = arr.length;
  if(arrLen<=1){
    return arr;
  }else{
    for(var i = 0;i < arrLen-1;i++){
      for(var j = i+1;j<arrLen;j++){
        if(arr[i]>arr[j]){
          var temp = arr[i];
          arr[i] = arr[j];
          arr[j] = temp;
        }
      }
    }
    return arr;
  }
}

js写快速排序

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function quickSort(arr){
  var arrLen = arr.length;
  if(arrLen<=1){
    return arr;
  }else{
    var left = [];
    var right = [];
    var basic = arr[0];
    for(var i = 1;i < arrLen; i++){
      if(arr[i]<basic){
        left.push(arr[i]);
      }else{
        right.push(arr[i]);
      }
    }
    return quickSort(left).concat(basic,quickSort(right));
  }
}

js写二分搜素

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function binarySearch(data,dist,startIndex,endIndex){
  var startIndex = startIndex || 0;
  var endIndex = endIndex || data.length-1;
  var midIndex = Math.floor((startIndex+endIndex)/2);
  if(dist == data[midIndex]){
    return midIndex;
  }else if(dist < data[startIndex]){
    return binarySearch(data,dist,startIndex,midIndex-1);
  }else{
    return binarySearch(data,dist,midIndex+1,endIndex);
  }
}

数组去重

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function uniq1(arr){
  var res = [];
  for(var i = 0;i < arr.length;i++){
    if(res.indexOf(arr[i])==-1){
      res.push(arr[i]);
    }
  }
  return res;
}
function uniq2(arr){
  var json = {};
  var res = [];
  for(var i = 0;i < arr.length;i++){
    if(!json[arr[i]]){
      json[arr[i]] = true;
      res.push(arr[i]);
    }
  }
  return res;
}

对象深度克隆

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function deepClone(obj){
  var buf;
  if(obj instanceof Array){
    buf = [];
    for(var i = 0; i < obj.length;i++){
      buf[i] = deepClone(obj[i]);
    }
    return buf;
  }else if(obj instanceof Object){
    buf = {};
    for(var k in obj){
      buf[k] = deepClone(obj[k]);
    }
    return buf;
  }else{
    return obj;
  }
}

斐波拉契方法

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function fibonacci(count){
  if(count<0){
    return count;
  }
 if(count <= 1){
   return 1;
 }
 var first = 1;
 var second = 1;
 var third = 0;
 for(var i = 2; i <= count;i++){
   third = first + second;
   first = second;
   second = third;
 }
 return third;
}

判断一个字符串中出现次数最多的字符，统计这个次数

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function getCharTimes(str){
  var json = {};
  for(var i = 0; i < str.length;i++){
    if(!json[str.charAt(i)]){
      json[str.charAt(i)] = 1;
    }else{
      json[str.charAt(i)]++;
    }
  }
  var max = 0;
  var maxIndex = '';
  for(var i in json){
    if(json[i]>max){
      max = json[i];
      maxIndex = i;
    }
  }
  return "出现最多的字符是"+maxIndex+"，次数为"+max;
}