443.string-compression.cpp

/*
 * @lc app=leetcode id=443 lang=cpp
 *
 * [443] String Compression
 *
 * https://leetcode.com/problems/string-compression/description/
 *
 * algorithms
 * Easy (35.97%)
 * Total Accepted:    36.5K
 * Total Submissions: 101.1K
 * Testcase Example:  '["a","a","b","b","c","c","c"]'
 *
 * Given an array of characters, compress it in-place.
 * 
 * The length after compression must always be smaller than or equal to the
 * original array.
 * 
 * Every element of the array should be a character (not int) of length 1.
 * 
 * After you are done modifying the input array in-place, return the new length
 * of the array.
 * 
 * 
 * Follow up:
 * Could you solve it using only O(1) extra space?
 * 
 * 
 * Example 1:
 * 
 * 
 * Input:
 * ["a","a","b","b","c","c","c"]
 * 
 * Output:
 * Return 6, and the first 6 characters of the input array should be:
 * ["a","2","b","2","c","3"]
 * 
 * Explanation:
 * "aa" is replaced by "a2". "bb" is replaced by "b2". "ccc" is replaced by
 * "c3".
 * 
 * 
 * 
 * 
 * Example 2:
 * 
 * 
 * Input:
 * ["a"]
 * 
 * Output:
 * Return 1, and the first 1 characters of the input array should be: ["a"]
 * 
 * Explanation:
 * Nothing is replaced.
 * 
 * 
 * 
 * 
 * Example 3:
 * 
 * 
 * Input:
 * ["a","b","b","b","b","b","b","b","b","b","b","b","b"]
 * 
 * Output:
 * Return 4, and the first 4 characters of the input array should be:
 * ["a","b","1","2"].
 * 
 * Explanation:
 * Since the character "a" does not repeat, it is not compressed.
 * "bbbbbbbbbbbb" is replaced by "b12".
 * Notice each digit has it's own entry in the array.
 * 
 * 
 * 
 * 
 * Note:
 * 
 * 
 * All characters have an ASCII value in [35, 126].
 * 1 <= len(chars) <= 1000.
 * 
 * 
 */
class Solution {
public:
    void printme(vector<char> chars){
        
        for(auto e: chars)
        {
            cout<<e<<' ';
        }
        cout<<endl;
        
    }
    int compress(vector<char>& chars) {
        int i = 0;
        int pos = 0;
        int N = chars.size();
        while(i < N){
            char cur = chars[i];
            int count = 1; i++;
            while(i < N && cur == chars[i]){
                i++;count++;
            }
            chars[pos++] = cur;
            if(count == 1)  continue;
            for(auto c: to_string(count))
                chars[pos++] = c;
        }
        return pos;
    }
};