javascript-binarySearch

前提： 数组已排序，且为正整数数组.

function brnarySearch(arg, arr) {
    var right = arr.length - 1;
    var left = 0;
    while(left <= right) {
          var mid = left + parseInt( (right - left) / 2 );
          if(arg < arr[mid]) right = mid - 1;
          else if(arg > arr[mid]) left = mid + 1;
          else return mid;
    }
    return -1;
}
var arr = [1, 3, 5, 7, 9, 11, 12, 44, 56];
console.log(brnarySearch(9, arr));