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443. String Compression

https://leetcode.com/problems/string-compression/

  • CTCI 1.6 String Compression

Python​

Python Itertools Groupby​

from itertools import groupby


class Solution:
    def compress(self, chars: List[str]) -> int:
        stack = []
        for key, group in groupby(chars):
            count = len(list(group))
            stack.append(key)
            if count > 1: stack.extend(list(str(count)))
        chars[:] = stack

Rust​

use std::iter::FromIterator;


impl Solution {
    pub fn compress(chars: &mut Vec<char>) -> i32 {
        let mut stack: Vec<char> = Vec::new();
        let mut i = 0;

        while i < chars.len() {
            let mut count = 1;
            while i + 1 < chars.len() && chars[i] == chars[i + 1] {
                i += 1;
                count += 1;
            }

            stack.push(chars[i]);

            if count > 1 {
                let count_chars: Vec<char> = count.to_string().chars().collect();
                stack.extend(count_chars);
            }

            i += 1;
        }

        *chars = stack;
        chars.len() as i32
    }
}