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  • Search in Rotated Sorted Array leetcode java

    描述
    Suppose a sorted array is rotated at some pivot unknown to you beforehand.
    (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).
    You are given a target value to search. If found in the array return its index, otherwise return -1.
    You may assume no duplicate exists in the array.
    分析
    二分查找,难度主要在于左右边界的确定。
    代码

     1 // LeetCode, Search in Rotated Sorted Array
     2 // 时间复杂度 O(log n),空间复杂度 O(1)
     3 class Solution {
     4     public static int search(int A[], int n, int target) {
     5        int first = 0, last = n;
     6        while (first != last) {
     7             int mid = (first + last) / 2;
     8             if (A[mid] == target)
     9                   return mid;
    10            if (A[first] <= A[mid]) {
    11                  if (A[first] <= target && target < A[mid])
    12                             last = mid;
    13                   else
    14                              first = mid + 1;
    15            } else {
    16                   if (A[mid] < target && target <= A[last-1])
    17                              first = mid + 1;
    18                   else
    19                               last = mid;
    20             }
    21          }
    22              return -1;
    23    }
    24 }
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  • 原文地址:https://www.cnblogs.com/ncznx/p/9167398.html
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