array driven Pattern
54 problems
Pattern pages help build reusable solving frames. Identify signals first, then explain state, transition, and edge handling.
Recognition Signals
- Look for efficiency in finding the insertion point, particularly using binary search for the best performance.
- Evaluate the candidate's understanding of merging intervals and their ability to handle edge cases such as no overlaps or full array merges.
- Checks the candidate's ability to optimize array traversal.
Solve Flow
- 1. Define the active state/window.
- 2. Update state while preserving invariants.
- 3. Validate with edge-heavy examples.
Common Misses
- Failing to consider edge cases such as inserting an interval that doesn't overlap with any existing ones.
- Failing to handle single-element ranges correctly.
- Forgetting to update the maximum after the last element if the array ends with 1s.
Recommended Ladder
Insert Interval
Given a sorted array of non-overlapping intervals, insert a new interval and merge any overlapping intervals.
Summary Ranges
Summary Ranges involves converting a sorted array of unique integers into a minimal list of range strings.
Max Consecutive Ones
Find the maximum sequence of consecutive 1s in a binary array using an efficient array-driven scanning approach.
Non-decreasing Array
Check if an array can become non-decreasing by modifying at most one element using an array-driven solution strategy.
Longest Continuous Increasing Subsequence
Find the length of the longest continuous increasing subsequence in an unsorted integer array using an array-driven solu…
1-bit and 2-bit Characters
Determine whether the last character in a binary array represents a one-bit character or a two-bit character.
Maximize Distance to Closest Person
Determine the seat placement that maximizes distance to the nearest person using a linear array scan strategy efficientl…
Monotonic Array
Determine if an integer array is entirely monotone increasing or decreasing using a clear array-driven approach.
Partition Array into Disjoint Intervals
Partition the array into two subarrays such that the left contains the smallest possible elements and the right contains…
Valid Mountain Array
The 'Valid Mountain Array' problem requires determining if an array meets the conditions of a valid mountain array using…
Distance Between Bus Stops
Compute the minimal distance between two bus stops on a circular route using an array-driven solution approach.
Element Appearing More Than 25% In Sorted Array
Identify the integer occurring more than 25% in a sorted array using a precise array-driven search strategy for efficien…
Replace Elements with Greatest Element on Right Side
Replace every element in an array with the greatest element on its right side, and replace the last element with -1.
Decompress Run-Length Encoded List
Decompress a run-length encoded list by expanding each pair into repeated values based on frequency.
Number of Times Binary String Is Prefix-Aligned
Count how many times a 1-indexed binary string becomes prefix-aligned as bits are flipped sequentially using an array-dr…
Kids With the Greatest Number of Candies
Determine which kids, after receiving extra candies, will have the greatest number of candies in a group.
Check If All 1's Are at Least Length K Places Away
Check if all 1's in a binary array are at least k places away from each other.
Number of Students Doing Homework at a Given Time
Count the number of students doing homework at a given time using an array-driven solution approach.
Shuffle the Array
Shuffle the Array requires an efficient approach to rearrange elements using an array-driven solution strategy with two …
Three Consecutive Odds
Determine if an integer array contains three consecutive odd numbers using a direct array-driven solution strategy for f…
Number Of Rectangles That Can Form The Largest Square
Determine how many rectangles can be trimmed to form the largest possible square using an array-driven solution strategy…
Check if Array Is Sorted and Rotated
Determine if a given integer array is sorted in non-decreasing order and then rotated, handling duplicates correctly.
Find Nearest Point That Has the Same X or Y Coordinate
Find the nearest point with the same x or y coordinate using Manhattan distance. Return its index or -1 if none exists.
Maximum Ascending Subarray Sum
Solve Maximum Ascending Subarray Sum by scanning once, extending rising runs, and resetting the running sum at each drop…
Minimum Distance to the Target Element
Solve Minimum Distance to the Target Element by scanning the array and tracking the smallest distance from start.
Remove One Element to Make the Array Strictly Increasing
Determine if removing a single element from an array can make it strictly increasing, using a careful index check approa…
Sum of Beauty in the Array
Calculate the sum of beauty for array elements using prefix and suffix tracking to optimize evaluation across indices ef…
Maximum Difference Between Increasing Elements
Find the maximum difference between two increasing elements in an array using a linear scan to track the minimum value e…
Smallest Index With Equal Value
Find the smallest index where the index mod 10 equals the value at that index in the given array.
All Divisions With the Highest Score of a Binary Array
Find all indices in a binary array where division score is maximized.
Count Equal and Divisible Pairs in an Array
Given an array, count pairs of elements that are equal and their indices product is divisible by a given integer.
Count Hills and Valleys in an Array
Count Hills and Valleys in an Array determines the number of hills and valleys in a given array by analyzing index neigh…
Find Closest Number to Zero
Identify the number in an integer array that is closest to zero, returning the larger one if tied.
The Employee That Worked on the Longest Task
Identify which employee spent the longest time on a task using an array-driven approach, analyzing each log entry effici…
Find the Maximum Divisibility Score
Determine the divisor with the highest count of divisible elements in an array using a clear array-driven strategy.
Number of Adjacent Elements With the Same Color
Calculate the number of adjacent elements sharing the same color after sequentially updating an initially zeroed array u…
Number of Employees Who Met the Target
Determine how many employees reach the required work hours using a direct array-driven counting approach.
Minimum Right Shifts to Sort the Array
Determine the minimum number of right shifts to sort a distinct integer array or return -1 if impossible using array ana…
Maximum Value of an Ordered Triplet I
Find the maximum value of a triplet in an array where indices follow the order i < j < k.
Maximum Value of an Ordered Triplet II
Solve Maximum Value of an Ordered Triplet II in linear time by tracking the best left difference and right multiplier.
Minimum Sum of Mountain Triplets I
Find the minimum sum of a mountain triplet in an array of integers, or return -1 if no valid triplet exists.
Minimum Sum of Mountain Triplets II
Find the minimum sum of a valid mountain triplet in an integer array, or return -1 if no valid triplet exists.
Maximum Area of Longest Diagonal Rectangle
Find the rectangle with the longest diagonal in a 2D array and return its area, prioritizing maximum area on ties.
Minimum Operations to Exceed Threshold Value I
Count how many numbers are below k, because each such value must be removed in Minimum Operations to Exceed Threshold Va…
Longest Strictly Increasing or Strictly Decreasing Subarray
Find the longest subarray in a given array that is either strictly increasing or strictly decreasing.
Find the Integer Added to Array I
Find the integer added to nums1 to make it equal to nums2 using an array-driven strategy.
Special Array I
Determine if an array is special by checking alternating parity for every adjacent pair in linear time.
Find Indices of Stable Mountains
Find the indices of stable mountains in an array of mountain heights based on a threshold.
Adjacent Increasing Subarrays Detection I
Check if an array contains two adjacent strictly increasing subarrays of length k using an array-driven approach efficie…
Button with Longest Push Time
Determine which button a child pressed the longest using an array-driven strategy to track time differences efficiently.
Count Subarrays of Length Three With a Condition
Determine how many subarrays of length three satisfy a sum condition on their first and third elements in an array.
Maximum Difference Between Adjacent Elements in a Circular Array
Find the maximum absolute difference between adjacent elements in a circular array using a straightforward array-driven …
Sum of Good Numbers
The problem asks for the sum of all good numbers in an array based on specific conditions of neighboring elements.
Minimum Cost to Reach Every Position
Calculate the minimum swap costs to reach each position in a line using a precise array-driven strategy for efficiency.