Problem of the day
You are given an array 'ARR' of integers of length N. Your task is to find the next smaller element for each of the array elements.
Next Smaller Element for an array element is the first element to the right of that element which has a value strictly smaller than that element.
If for any array element the next smaller element does not exist, you should print -1 for that array element.
For Example:
If the given array is [ 2, 3, 1], we need to return [1, 1, -1]. Because for 2, 1 is the Next Smaller element. For 3, 1 is the Next Smaller element and for 1, there is no next smaller element hence the answer for this element is -1.
The first line of input contains an integer ‘T’ which contains the number of test cases.
The first line of each test case contains an integer 'N' denoting the number of elements in the array 'ARR'.
The second line of each test case contains 'N' space-separated integers denoting the array 'ARR'.
Output Format:
For each test case, print a single line containing 'N' space-separated integers denoting the value of Next Smaller Element for each of the 'N' array elements.
The output for each test case will be printed in a separate line.
Note:
You do not need to print anything, it has already been taken care of. Just implement the given function.
1 <= T <= 10
1 <= N <= 10 ^ 5
0 <= ARR [i] <= 10 ^ 9
Time Limit: 1sec.
2
4
2 1 4 3
3
1 3 2
1 -1 3 -1
-1 2 -1
For the first test case :
1) For ARR [1] = 2 , the next smaller element is 1.
2) For ARR [2] = 1 , the next smaller element is -1 as no element in the array has value smaller than 1.
3) For ARR [3] = 4 , the next smaller element is 3.
4) For ARR [4] = 3 , the next smaller element is -1 as no element exists in the right of it.
Hence, we will return the array [ 1, -1, 3, -1] in this case.
For the second test case :
1) For ARR [1] = 1 , the next smaller element is -1 as no element in the array has value smaller than 1.
2) For ARR [2] = 3 , the next smaller element is 2.
3) For ARR [3] = 2 , the next smaller element is -1 as no element exists in the right of it.
Hence we will return the array [ -1, 2, -1 ] in this case.
2
4
1 2 3 4
2
5 0
-1 -1 -1 -1
0 -1
Try to find out the Next Smaller Element for each of the array elements by iterating to the right of that element and comparing it with each element.
The idea is to find the Next Smaller Element for each array element one by one. To find the Next Smaller for an array element we will start moving to the right of that element and will try to find the first element having a value smaller than that element and set the Next Smaller Element as that element and end our search. If we reach the end of the array without finding any such element then we will set the next smaller element as -1 for that element.
Let ans be an array of length N that stores the Next Smaller Elements.
Steps :
O(N ^ 2), where ‘N’ is the number of elements in the array.
We are traversing the array. And for each element we are checking all the elements to the right of it. Thus, at most ‘N’ searches for each index. Hence, the total time complexity is O(N^2).
O(1), as we are using constant extra space.