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704. Binary Search
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:= [-1,0,3,5,9,12],numstarget = 9 Output: 4 Explanation: 9 exists innums and its index is 4
Example 2:
Input:= [-1,0,3,5,9,12],numstarget = 2 Output: -1 Explanation: 2 does not exist innums so return -1
Note:
-
You may assume that all elements in
numsare unique. -
nwill be in the range[1, 10000]. -
The value of each element in
numswill be in the range[-9999, 9999].
思路分析
二分查找
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一刷
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二刷
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/**
* @author D瓜哥 · https://www.diguage.com
* @since 2024-07-01 15:22:49
*/
public int search(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return -1;
}
int left = 0;
int right = nums.length - 1;
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 - 1;
}
}
return -1;
}
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/**
* @author D瓜哥 · https://www.diguage.com
* @since 2024-09-14 19:52:26
*/
public int search(int[] nums, int target) {
int left = 0, right = nums.length - 1;
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 - 1;
}
}
return -1;
}