[LeetCode] 704. Binary Search
grandyang opened this issue · comments
Given a sorted (in ascending order) integer array nums
of n
elements and a target
value, write a function to search target
in nums
. If target
exists, then return its index, otherwise return -1
.
Example 1:
Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4
Example 2:
Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1
Note:
- You may assume that all elements in
nums
are unique. n
will be in the range[1, 10000]
.- The value of each element in
nums
will be in the range[-9999, 9999]
.
这道题就是最基本的二分搜索法了,这是博主之前总结的LeetCode Binary Search Summary 二分搜索法小结的四种之中的第一类,也是最简单的一类,写法什么很模版啊,注意right的初始化值,还有while的循环条件,以及right的更新值,这三点不同的人可能会有不同的写法,选一种自己最习惯的就好啦,参见代码如下:
class Solution {
public:
int search(vector<int>& nums, int target) {
int left = 0, right = nums.size();
while (left < right) {
int mid = left + (right - left) / 2;
if (nums[mid] == target) return mid;
else if (nums[mid] < target) left = mid + 1;
else right = mid;
}
return -1;
}
};
类似题目:
Search in a Sorted Array of Unknown Size
参考资料:
https://leetcode.com/problems/binary-search