검색 Searching

선형검색

function linearSearch(arr,val){
      for(let i=0; i <arr.length; i ++){
        if  (arr[i] === val){
            return  i
        }
      }
  return -1;
}

linearSearch([32,56,1,2],1)

이진 검색(Binary Search)

function binarySearch(arr,elem){
      let start = 0;
      // -1 빼지 않으면 배열의 범위를 벗어남
      let  end = arr.length -1;
      let middle = Math.floor((start + end) / 2);
      console.log(start,end,middle)
  while(arr[middle] !== elem && (start + end)/ 2){
    if(elem < arr[middle])  end = middle -1;      
     else  start = middle +1;
     middle = Math.floor((start + end) / 2);
  }
   return arr[middle] === elem ? middle : -1;  
}

binarySearch([2,5,6,8,10,22,35,44],10)
// [2,5,6,8,10,22,35,44],15
//  S     M           E