10+ Hike Interview Questions and Answers for Freshers

Find the maximum area of a submatrix with all 1's in a binary matrix.

• Iterate over each cell in the matrix and calculate the maximum area of submatrix with that cell as the top-left corner.

• Use dynamic programming to keep track of the maximum width of 1's ending at each cell.

• Update the maximum area as you iterate through the matrix.

• Return the maximum area found.

The minimum number of swaps required to sort a given array of distinct elements in ascending order.

• Use a graph-based approach to find cycles in the array for swapping

• Count the number of swaps needed to sort the array

• Example: For [4, 3, 2, 1], 2 swaps are needed to sort it to [1, 2, 3, 4]

Find the maximum path sum in a binary tree with 'N' nodes.

• Traverse the binary tree to find the maximum path sum.

• Keep track of the maximum sum encountered so far.

• Consider all possible paths in the tree to find the maximum sum.

• Example: For input 1 2 3 4 -1 5 6 -1 -1 -1 -1 -1 -1, the maximum path sum is 16.

Find the maximum sum of a simple path between any two nodes in a binary tree.

• Use a recursive approach to traverse the binary tree and calculate the maximum sum path.

• Keep track of the maximum sum path found so far while traversing the tree.

• Consider negative values in the path sum calculation to handle cases where the path can skip nodes.

• Update the maximum sum path if a new path with a higher sum is found.

Convert infix expression to postfix expression.

• Use a stack to keep track of operators and operands.

• Follow the rules of precedence for operators.

• Handle parentheses to ensure correct order of operations.

Find the maximum area of a submatrix consisting entirely of 1's in a binary matrix.

• Iterate over each cell in the matrix and calculate the maximum area of a submatrix with that cell as the top-left corner.

• Use dynamic programming to keep track of the maximum width of 1's ending at each cell in the current row.

• Update the maximum area as you iterate through the matrix and consider each cell as the bottom-right corner of the submatrix.

Convert a valid Prefix expression to its corresponding Infix expression.

• Use a stack to store operands and operators while traversing the prefix expression from right to left.

• Pop operands from the stack and form the infix expression by placing them between corresponding operators.

• Handle the precedence of operators to ensure correct order of operations in the infix expression.

Find the maximum difference between elements in a matrix with specific conditions.

• Iterate through all possible pairs of indices (a, b) and (c, d) where c > a and d > b.

• Calculate the difference between mat[c][d] and mat[a][b] for each pair.

• Keep track of the maximum difference found so far.

• Return the maximum difference as the final result.

Code to get max and second max element of a stack in O(1) complexity.

• Create two variables to store max and second max values

• Update the variables whenever a new element is pushed or popped from the stack

• Return the max and second max values when required

Code to search a given number in a biotonic array with O(logn) time complexity.

• Use binary search to find the peak element in the array.

• Divide the array into two subarrays and perform binary search on each subarray.

• Return the index of the element if found, else return -1.

Sort a rotated sorted array in O(n) time without extra space

• Find the index of the minimum element using binary search

• Reverse the two subarrays on either side of the minimum element

• Reverse the entire array

• Example: [4,5,6,7,0,1,2] -> [0,1,2,4,5,6,7]

Finding two pairs with a given sum in a BST using O(log n) space.

• Traverse the BST in-order and store the nodes in an array

• Use two pointers approach to find the pairs with the given sum

• Time complexity: O(n), Space complexity: O(log n)

• Optimized approach: Use two stacks to traverse the BST in-order and find the pairs

• Time complexity: O(log n), Space complexity: O(log n)

To select k random numbers from an infinite stream of array with equal probability.

• Use reservoir sampling algorithm to randomly select k numbers from the stream

• Maintain a reservoir array of size k to store the selected numbers

• For each incoming number, generate a random number between 0 and the total count of numbers seen so far

• If the generated number is less than k, replace the corresponding number in the reservoir array with the incoming number

• At the end, the reservoir array...read more

Manholes are round because it prevents them from falling into the hole and allows for easy movement of the cover.

• Round covers cannot fall into the hole as they cannot fit through diagonally

• Round covers can be easily moved in any direction

• Round shape distributes weight evenly

• Round shape is easier to manufacture and install