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Backspace String Compare Backwards in Constant Space
Compare typed strings with backspaces in O(1) space, scanning backwards. Python solution and complexity analysis for the two pointers interview pattern.
Tag
Two Pointers
Articles tagged Two Pointers on The Augmented Dev.
12 articles
3 min read
Container With Most Water and the Greedy Pointer Proof
Maximize trapped area and prove the greedy pointer move is safe. Python solution and complexity analysis for the two pointers interview pattern.
3 min read
Move Zeroes: In Place Partitioning With a Write Pointer
Push all zeroes to the back in one pass, preserving order. Python solution and complexity analysis for the two pointers interview pattern.
3 min read
Remove Duplicates In Place: The Reader Writer Pointer Trick
Dedupe a sorted array in place with a reader and a writer index. Python solution and complexity analysis for the two pointers interview pattern.
3 min read
Sort Colors: The Dutch National Flag in One Pass
Three-way partition of 0s, 1s and 2s in one pass, no counting. Python solution and complexity analysis for the two pointers interview pattern.
3 min read
Squares of a Sorted Array Without Sorting Again
Square a sorted array with negatives and stay O(n), no re-sort. Python solution and complexity analysis for the two pointers interview pattern.
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3Sum Closest: Tracking the Best Miss With Two Pointers
Nearest triplet sum to a target, converging on the smallest gap. Python solution and complexity analysis for the two pointers interview pattern.
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3Sum: Sorting Plus Two Pointers, With Duplicate Handling
All unique triplets summing to zero — dedupe without a set of tuples. Python solution and complexity analysis for the two pointers interview pattern.
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Trapping Rain Water With Converging Boundary Maxima
The classic hard: O(1)-space water trapping via boundary maxima. Python solution and complexity analysis for the two pointers interview pattern.
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Two Sum on a Sorted Array: The Two Pointers Opener
Find a pair summing to target in one pass and O(1) space. Python solution and complexity analysis for the two pointers interview pattern.
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Valid Palindrome II: One Deletion, Two Branches
Palindrome check with one allowed deletion — branch only on mismatch. Python solution and complexity analysis for the two pointers interview pattern.
3 min read
Valid Palindrome: Clean Two Pointer String Scanning
Check a messy string is a palindrome without building a filtered copy. Python solution and complexity analysis for the two pointers interview pattern.