HackMD
704.Binary Search
tags: Easy,Array,Binary Search
題目描述
Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.
You must write an algorithm with O(log n) runtime complexity.
範例
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
Constraints:
- 1 <=
nums.length<= 104 - -104 <
nums[i],target< 104 - All the integers in
numsare unique. numsis sorted in ascending order.
解答
Javascript
function search(nums, target) {
let min = 0;
let max = nums.length - 1;
while (max >= min) {
const mid = Math.floor((max + min) / 2);
if (nums[mid] === target) return mid;
if (nums[mid] > target) {
max = mid - 1;
} else {
min = mid + 1;
}
}
return -1;
}
MarsgoatApr 1, 2023
Python
class Solution:
def search(self, nums: List[int], target: int) -> int:
L, R = 0, len(nums)
while L < R:
M = (L + R) // 2
n = nums[M]
if n == target:
return M
if n > target:
R = M
else:
L = M + 1
return -1
