Problem of the day
You are given a sorted array A consisting of N integers. Your task is to find the magic index in the given array.
Note :1. A magic index in an array A[0 ... N - 1] is defined to be an index i such that A[i] = i.
2. The elements in the array can be negative.
3. The elements in the array can be repeated multiple times.
4. There can be more than one magic index in an array.
The first line of the input contains an integer T denoting the number of test cases.
The first line of each test case contains one integer N, as described in the problem statement.
The second line of each test case contains N space-separated integers, representing the elements of the array.
Output Format :
For each test case print in a new line, one integer representing the magic index of the given array or -1 if there does not exist any magic index for the given array.
In case there is more than one magic index, return any of them.
1 <= T <= 10
1 <= N <= 10^5
-10^9 <= A[i] <= 10^9
Time Limit: 1sec
1
5
-5 -1 2 1 9
2
The output is 2 because A[2] = 2 and hence 2 is the magic index.
2
5
2 3 4 5 6
6
-1 -1 -1 4 4 4
-1
4
Check each index one by one.
O(N), where N is the number of elements in the array.
Since we iterate through the given array only once hence the time complexity will be O(N).
O(1).
Since we are using constant extra space to store our answer, so the space complexity is O(1).