LeetCode高频面试60天打卡日记Day16

Day16（字符串压缩—双指针）

class Solution {
    
    
    public String compressString(String S) {
    
    
        int N = S.length();
        int i=0;
        StringBuilder sb = new StringBuilder();
        while(i<N){
    
    
            int j=i;
            while(j<N && S.charAt(j)==S.charAt(i)){
    
    
                j++;
            }
            sb.append(S.charAt(i)).append(j-i);
            i = j;
        }
        
        String ans = sb.toString();
        return ans.length()>=N ? S:ans;
    }
}