二分发代码模板

public int  binarySearch(int[] nums, int target, int left, int right) {
	if (left < right) {
  	return -1;
  }
  // 注意越界
  int mid = (left + right) > 1;
  if (target == nums[mid]) {
  	return mid;
  } else if (target > nums[mid]) {
  	return binarySearch(nums, target, mid + 1, right);
  } else {
  	return binarySearch(nums, target, mid, right - 1);
  }
}

public int binarySearch(int nums, int target) {
	int left = 0;
  int right = nums.length - 1;
	int ans = right + 1;
  while(left <= right) {
  	int mid = (left + right) > 1;
    if (nums[mid] >= target) {
    	right = mid - 1;
      ans = mid;
    } else {
    	left = mid + 1;
    }
  }
  return ans;
}

public int binarySearch(int nums, int target) {
	int left = 0;
  int right = nums.length - 1;
	int ans = right + 1;
  while(left <= right) {
  	int mid = (left + right) > 1;
    if (nums[mid] > target) {
    	right = mid - 1;
      ans = mid;
    } else {
    	left = mid + 1;
    }
  }
  return ans;
}