three pointers pattern

Master Wiggle Sort II (LeetCode 324): Virtual Indexing & 3-Way Partition | Day 6 of 180

by

2. Pattern Recognition: Why Dutch National Flag Again? In Day 5, we solved Sort Colors by partitioning 0, 1, 2 around fixed values. In Wiggle Sort II: If we find the median element of the array: This is precisely the Dutch National Flag (3-Way Partition) pattern! The only challenge is placing elements into odd/even slots … Read more

Master Sort Colors (LeetCode 75): Dutch National Flag 3-Way Partition | Day 5 of 180

by
Master Sort Colors (LeetCode 75): Dutch National Flag 3-Way Partition | Day 5 of 180

2. Pattern Recognition: Why Dutch National Flag? In standard two-pointer partitioning (such as in QuickSort), you partition elements into two categories: smaller than pivot and greater than pivot. However, when a problem involves exactly three distinct categories (like 0, 1, 2, negative/zero/positive, or < pivot, == pivot, > pivot), a 2-way split requires multiple passes. … Read more