代码随想录刷题day 8 | 344.反转字符串 541. 反转字符串II 卡码网：54.替换数字

344. 反转字符串

class Solution {
    public void reverseString(char[] s) {
        int left = 0, right = s.length - 1;
        while(left < right){
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
            left++; right--;
        }
    }
}

541. 反转字符串 II

class Solution {
    public String reverseStr(String s, int k) {
        char[] str = s.toCharArray();
        int iter = s.length() / (2 * k);
        for(int i = 0; i <= str.length; i+=2*k){
            int left = i, right = Math.min(s.length() - 1, left + k - 1);
            while(left < right){
                char tmp = str[left];
                str[left] = str[right];
                str[right] = tmp;
                left++; right--;
            }
        }
        return new String(str);
    }
}

54. 替换数字（第八期模拟笔试）

import java.util.Scanner;
public class Main{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        int len = 0;
        for(char c : s.toCharArray()){
            if(c >= '0' && c <= '9') len += 5;
            len++;
        }
        char[] ans = new char[len];
        for(int i = 0; i < s.length(); i++){
            ans[i] = s.charAt(i);
        }
        int right = ans.length - 1, left = s.length() - 1;
        while(left >= 0){
            if(ans[left] >= '0' && ans[left] <= '9'){
                ans[right--] = 'r';
                ans[right--] = 'e';
                ans[right--] = 'b';
                ans[right--] = 'm';
                ans[right--] = 'u';
                ans[right--] = 'n';
                left--;
            }else{
                ans[right--] = ans[left--];
            }
        }
        System.out.println(new String(ans));
    }
}