【Leetcode】Search in Rotated Sorted Array II

Follow up for "Search in Rotated Sorted Array":
What if duplicates are allowed?

Would this affect the run-time complexity? How and why?

Write a function to determine if a given target is in the array.

 1 class Solution {
 2 public:
 3     bool search(int A[], int n, int target) {
 4         int start = 0, end = n - 1;
 5         while (start <= end) {
 6             int mid = (start + end) / 2;
 7             if (A[mid] == target) return true;
 8             if (A[start] < A[mid]) {
 9                 if (A[start] <= target && A[mid] > target) {
10                     end = mid - 1;
11                 } else {
12                     start = mid + 1;
13                 }
14             } else if (A[start] > A[mid]) {
15                 if (A[mid] < target && A[end] >= target) {
16                     start = mid + 1;
17                 } else {
18                     end = mid - 1;
19                 }
20             } else {
21                 ++start;
22             }
23         }
24         return false;
25     }
26 };
View Code

整体上与上题(Search in Rotated Sorted Array)差别不大,额外的是:若数组中存在重复元素,那么区间首尾元素相等时无法确定区间内是否发生过rotate,此时跳过首元素继续找。

posted @ 2014-03-16 19:20  小菜刷题史  阅读(237)  评论(0编辑  收藏  举报