JavaScript でBinarySearch

binary_search.js

function binary_search(a, start_idx, end_idx, target){
  var start = start_idx;
  var end = end_idx;
  while((end - start) >= 0){
    var mid = Math.floor((end + start) / 2);
    if(a[mid] === target){
    	return {
    		flag: true,
    		index: mid
    	};
    }else if(a[mid] > target){
	end = mid - 1;
    }else {
    	start = mid + 1;
    }
  }
  return {
  	flag: false,
  	index: -1
  };
}