What is the time complexity of the longest increasing subsequence problem using
Practice Questions
Q1
What is the time complexity of the longest increasing subsequence problem using dynamic programming?
O(n)
O(n log n)
O(n^2)
O(2^n)
Questions & Step-by-Step Solutions
What is the time complexity of the longest increasing subsequence problem using dynamic programming?
Step 1: Understand the problem. The longest increasing subsequence (LIS) is a sequence of numbers where each number is larger than the previous one.
Step 2: Identify the input size. Let 'n' be the number of elements in the array.
Step 3: Use dynamic programming to solve the problem. Create an array 'dp' where dp[i] represents the length of the longest increasing subsequence that ends with the element at index i.
Step 4: Initialize each element of 'dp' to 1 because the minimum length of an increasing subsequence that ends at any element is 1 (the element itself).
Step 5: Use two nested loops to fill the 'dp' array. The outer loop goes through each element, and the inner loop checks all previous elements to see if they can form an increasing subsequence with the current element.
Step 6: For each pair of indices (i, j), if the element at index j is less than the element at index i, update dp[i] to be the maximum of its current value and dp[j] + 1.
Step 7: After filling the 'dp' array, the length of the longest increasing subsequence will be the maximum value in the 'dp' array.
Step 8: Analyze the time complexity. The outer loop runs 'n' times and for each iteration, the inner loop also runs up to 'n' times, resulting in O(n^2) time complexity.
