leetcode 540. Single Element in a Sorted Array 题解
2017-08-22 20:13
477 查看
原题:
Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element that appears only once.
Example 1:
Example 2:
Note: Your solution should run in O(log n) time and O(1) space.
翻译:
给一个有序整数数组,除了一个数,其余数都会出现两次,找到这个数并返回。
(你的程序必须在O(log n)的时间,O(1)的空间内运行完)
思路:
这是一个binary search的题目,找到中点后看这个单一的数在左边还是在右边,每次都能把数组的长度削减一半。
程序:
class Solution {
public:
int singleNonDuplicate(vector<int>& nums) {
if(nums.size() % 2 == 0) {
return 0;
}
int low = 0, high = (int)nums.size() - 1;
while(low < high) {
int mid = (low + high)/2;
if(mid % 2 == 0) {
if(nums[mid] == nums[mid + 1]) {
low = mid + 2;
}else {
high = mid - 2;
}
}else {
if(nums[mid] == nums[mid + 1]) {
high = mid - 1;
}else {
low = mid + 1;
}
}
}
return nums[low];
}
};
(如果思路不好或者代码有能改进的地方请留言告诉我,谢谢。)
Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element that appears only once.
Example 1:
Input: [1,1,2,3,3,4,4,8,8] Output: 2
Example 2:
Input: [3,3,7,7,10,11,11] Output: 10
Note: Your solution should run in O(log n) time and O(1) space.
翻译:
给一个有序整数数组,除了一个数,其余数都会出现两次,找到这个数并返回。
(你的程序必须在O(log n)的时间,O(1)的空间内运行完)
思路:
这是一个binary search的题目,找到中点后看这个单一的数在左边还是在右边,每次都能把数组的长度削减一半。
程序:
class Solution {
public:
int singleNonDuplicate(vector<int>& nums) {
if(nums.size() % 2 == 0) {
return 0;
}
int low = 0, high = (int)nums.size() - 1;
while(low < high) {
int mid = (low + high)/2;
if(mid % 2 == 0) {
if(nums[mid] == nums[mid + 1]) {
low = mid + 2;
}else {
high = mid - 2;
}
}else {
if(nums[mid] == nums[mid + 1]) {
high = mid - 1;
}else {
low = mid + 1;
}
}
}
return nums[low];
}
};
(如果思路不好或者代码有能改进的地方请留言告诉我,谢谢。)
相关文章推荐
- leetcode 540. Single Element in a Sorted Array
- [LeetCode] 540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array (Medium)
- (Java) LeetCode 540. Single Element in a Sorted Array —— 有序数组中的单一元素
- LeetCode 540. Single Element in a Sorted Array
- {LeetCode} 540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array
- [LeetCode]540. Single Element in a Sorted Array
- [Leetcode] 540. Single Element in a Sorted Array 解题报告
- LeetCode | 540. Single Element in a Sorted Array
- [LeetCode]540. Single Element in a Sorted Array
- python--leetcode540. Single Element in a Sorted Array
- LeetCode 540. Single Element in a Sorted Array
- 【LeetCode】540. Single Element in a Sorted Array 解题报告
- 【LeetCode】540. Single Element in a Sorted Array
- leetcode 540. Single Element in a Sorted Array
- LeetCode - 540. Single Element in a Sorted Array
- [LeetCode] Single Element in a Sorted Array 有序数组中的单独元素
- 540. Single Element in a Sorted Array