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FindFirstAndLastIndex
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FindFirstAndLastIndex
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//This is same solution we discussed in class.
//Time Complexity : O(log n)
// Space Complexity : O(1)
// Did this code successfully run on Leetcode : Yes
// Any problem you faced while coding this : No
class Solution {
public int[] searchRange(int[] nums, int target) {
if(nums == null || nums.length == 0) return new int[] {-1, -1};
int n = nums.length -1 ;
int first = binarySearchFirst(nums,target,0,n);
if(first ==-1) return new int[] {-1, -1};
int last = binarySearchLast(nums,target,first,n);
return new int[] {first, last};
}
private int binarySearchFirst(int[] nums, int target, int low, int high) {
while(low<=high) {
int mid = low + (high - low) /2;
if(nums[mid] == target) {
if(mid == 0 || nums[mid - 1] < nums[mid]) {
return mid;
} else {
high = mid -1;
}
} else if(nums[mid] > target) {
high = mid - 1;
} else {
low = mid + 1;
}
}
return -1;
}
private int binarySearchLast(int[] nums, int target, int low, int high) {
while(low<=high) {
int mid = low + (high - low) /2;
if(nums[mid] == target) {
if(mid == high || nums[mid + 1] > nums[mid]) {
return mid;
} else {
low = mid + 1;
}
} else if(nums[mid] > target) {
high = mid - 1;
} else {
low = mid + 1;
}
}
return -1;
}
}