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Monotonic Stack Fundamentals Monotonic stacks enable linear preprocessing to find: Prefix/suffix maximum/minimum positions in sequences Next greater/smaller element positions for each index Problem B3666: Suffix Maximum Positions Given a dynamically growing array, after each insertion, find all suffix maximum indices and output their XOR sum. ...

Core Concept The monotonic stack is a powerful technique for solving next greater elemant problems efficiently. The key insight is to maintain a stack that keeps candidate elements in a specific order, allowing us to find the next greater element for each position in a single pass. Fundamental Example Problem: Given an array, find the next grea ...

Minimum Insertions to Balance Parentheses Validating and repairing parenthesis strings requires tracking the relationship between opening and closing symbols. The algorithm monitors the current balance of unmatched left parentheses while counting necessary insertions. As we traverse the string, left parentheses increment a balance counter, whil ...