Given two positive integers low and high represented as strings, find the count of stepping numbers in the inclusive range [low, high].
A stepping number is an integer such that all of its adjacent digits have an absolute difference of exactly 1.
Return an integer denoting the count of stepping numbers in the inclusive range [low, high].
Since the answer may be very large, return it modulo 109 + 7.
Note: A stepping number should not have a leading zero.
Example 1:
Input: low = "1", high = "11" Output: 10 Explanation: The stepping numbers in the range [1,11] are 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. There are a total of 10 stepping numbers in the range. Hence, the output is 10.
Example 2:
Input: low = "90", high = "101" Output: 2 Explanation: The stepping numbers in the range [90,101] are 98 and 101. There are a total of 2 stepping numbers in the range. Hence, the output is 2.
Constraints:
1 <= int(low) <= int(high) < 101001 <= low.length, high.length <= 100low and high consist of only digits.low and high don't have any leading zeros.This approach involves examining all possible combinations to find the solution by iterating over each element. While simple, the method may not be efficient for large datasets due to its time complexity.
The function bruteForceSolution computes the sum of all possible pairs in an array using nested loops. This involves iterating through each element and pairing it with all the subsequent elements.
C++
Java
Python
C#
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Time Complexity: O(n^2)
Space Complexity: O(1)
This approach improves efficiency by leveraging a mathematical observation or data structure to avoid redundant calculations, significantly reducing time complexity.
This C function computes the sum of all possible integer pairs by calculating the total sum and multiplying each element by the size - 1, effectively counting its contribution to all possible pairs.
C++
Java
Python
C#
JavaScript
Time Complexity: O(n)
Space Complexity: O(1)
| Approach | Complexity |
|---|---|
| Approach 1: Brute Force Method | Time Complexity: O(n^2) |
| Approach 2: Optimized Pair Calculation Using Single Loop | Time Complexity: O(n) |
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