‘Find First and Last Position of Element in Sorted Array’ in LeetCode (Medium)
📌 Problem
https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/
📌 Answer
The point
- binary search : time complextiy is O(logN)
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class Solution {
public int[] searchRange(int[] nums, int target) {
int[] result = new int[2];
result[0] = findFirst(nums, target);
result[1] = findLast(nums, target);
return result;
}
private int findFirst(int[] nums, int target) {
int idx = -1;
int start = 0;
int end = nums.length - 1;
while (start <= end) {
int mid = (start + end) / 2;
// here is difference
if (nums[mid] >= target)
end = mid - 1;
else
start = mid + 1;
if (nums[mid] == target) idx = mid;
}
return idx;
}
private int findLast(int[] nums, int target) {
int idx = -1;
int start = 0;
int end = nums.length - 1;
while (start <= end) {
int mid = (start + end) / 2;
// here is difference
if (nums[mid] <= target)
start = mid + 1;
else
end = mid - 1;
if (nums[mid] == target) idx = mid;
}
return idx;
}
}
/**
[Question]
- Find First and Last Position of Element in Sorted Array
- find the starting and ending position of a given target value.
- If target is not found in the array, return [-1, -1].
[Condition]
- 0 <= nums.length <= 10.5
- 10.9 <= nums[i] <= 10.9
- -10.9 <= target <= 10.9
**/
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