Build a Huffman Tree From Symbol Frequencies

Coding: Build a Huffman Tree From Frequencies Given symbols and their frequencies (weights), build a Huffman tree and output the Huffman code for each symbol. Input First line: integer n (#symbols) Next n lines: a symbol string s and an integer frequency f. Output Print n lines: s code, where code is a 0/1 Huffman code. Rules: Must be prefix-free. If multiple optimal solutions exist, break ties deterministically: always merge the two smallest-frequency nodes; if equal frequency, compare the node's minimal symbol lexicographically; the smaller one becomes the left child (edge 0). If n == 1, output code 0. Constraints n and total symbol length up to 2e5. Example Input 4 a 5 b 9 c 12 d 13 Output a 00 b 01 c 10 d 11