面试题 10.03. 搜索旋转数组
搜索旋转数组。给定一个排序后的数组,包含n个整数,但这个数组已被旋转过很多次了,次数不详。请编写代码找出数组中的某个元素,假设数组元素原先是按升序排列的。若有多个相同元素,返回索引值最小的一个。
示例1:
输入: arr = [15, 16, 19, 20, 25, 1, 3, 4, 5, 7, 10, 14], target = 5
输出: 8(元素5在该数组中的索引)
示例2:
输入:arr = [15, 16, 19, 20, 25, 1, 3, 4, 5, 7, 10, 14], target = 11
输出:-1 (没有找到)
class Solution {
public:
int search(vector<int>& nums, int target) {
int left = 0, right = nums.size() - 1;
while(left <= right){
int mid = (left + right) / 2;
if(nums[left] == target){
return left;
}
//中间数与左边数相等
if(nums[left] == nums[mid] ){
++left;
continue;
}
if(nums[mid] == target){
right = mid;
}else if(nums[left] < nums[mid]){
//nums[mid] != target
if(nums[left] <= target && target < nums[mid]){
right = mid - 1;
} else {
left = mid + 1;
}
} else {
if(nums[mid] < target && target <= nums[right]){
left = mid + 1;
} else {
right = mid - 1;
}
}
}
return -1;
}
};
作者:Tzetco
链接:https://leetcode-cn.com/problems/search-rotate-array-lcci/solution/mian-shi-ti-1003-sou-suo-xuan-zhuan-shu-f9q8t/
来源:力扣(LeetCode)
著作权归作者所有。商业转载请联系作者获得授权,非商业转载请注明出处。