Review系列三大基础排序

Posted 2021-06-29 Smile沛沛

冒泡排序

数组当前项跟后一项进行对比，如果当前项比后一项大那么两项交换位置

let ary = [23,31,4,7,3,9]

function bubble(ary){
  for(let i = 0;i<ary.length-1;i++){	//控制比较轮数
    for(let j = 0;j<ary.length-1-i;j++){		//每一轮比较的次数
      ary[j]>ary[j+1]?[ary[j],ary[j+1]]=[ary[j+1],ary[j]]:null
    }
  }
  return ary
}

插入排序

类似于抓牌

let ary = [23,31,4,7,3,9]

function insert(ary){
  let handle = [];
  handle.push(ary[0])
  for(let i = 1;i<ary.length;i++){
    for(let j = handle.length-1;j>=0;j--){
      if(ary[i]>handle[j]){
        handle.splice(j+1,0,ary[i]);			//把ary[i]放到handle[j]的后面；及放到handle[j+1]前面
        break;
      }
      if(j===0){
        handle.unshift(ary[i]);		//已经比较到最前面就插入数组首部
      }
    }
  }
  return handle;
}

快速排序

找到数组中的中间项，然后将其从原来数组中移除，并且获取这个中间项值。依次拿数组中的每项跟中间项进行对比，小的放左边大的放右边

 let ary = [23,31,4,7,3,9]

function quick(ary){
  if(ary.length<=1){return ary}
  let middleIndex = Math.floor(ary.length/2)
  let middleVal = ary.splice(middleIndex,1)[0]
  let leftary = [],
  		rightary = []
  for(let i = 0;i<ary.length;i++){
  	ary[i]<middleVal?leftary.push(ary[i]):rightary.push(ary[i])
    
  }
  return (quick(leftary)).concat(middleVal,quick(rightary))
}