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Last Occurrence - Medium

时间:2018-12-16 11:06:20      阅读:95      评论:0      收藏:0      [点我收藏+]

标签:ast   pre   null   log   index   tar   style   nbsp   duplicate   

Given a target integer T and an integer array A sorted in ascending order, find the index of the last occurrence of T in A or return -1 if there is no such index.

Assumptions

  • There can be duplicate elements in the array.

Examples

  • A = {1, 2, 3}, T = 2, return 1
  • A = {1, 2, 3}, T = 4, return -1
  • A = {1, 2, 2, 2, 3}, T = 2, return 3

Corner Cases

  • What if A is null or A is array of zero length? We should return -1 in this case.

 

time: O(log(n)), space: O(1)

public class Solution {
  public int lastOccur(int[] array, int target) {
    // Write your solution here
    if(array == null || array.length == 0) return -1;
    int left = 0, right = array.length - 1;
    while(left + 1 < right) {
      int mid = left + (right - left) / 2;
      if(array[mid] == target)
        left = mid;
      else if(array[mid] > target)
        right = mid;
      else
        left = mid;
    }
    if(array[right] == target)
      return right;
    else if(array[left] == target)
      return left;
    else
      return -1;
  }
}

 

Last Occurrence - Medium

标签:ast   pre   null   log   index   tar   style   nbsp   duplicate   

原文地址:https://www.cnblogs.com/fatttcat/p/10125617.html

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