Java Search

BinarySearch.java

//binary search on a sorted arrays
public static int binarySearch(int[] nums,int target,int left,int right){
  while (left <= right) {
    //这里需要注意，计算mid
    int mid = left + ((right - left) >> 1);
    if (nums[mid] == target) {
      return mid;
    }else if (nums[mid] < target) {
          //这里需要注意，移动左指针
             left  = mid + 1;
          }else if (nums[mid] > target) {
                  //这里需要注意，移动右指针
                  right = mid - 1;
                }
  }
  //没有找到该元素，返回 -1
  return -1;
 }