344. 反转字符串

LeetCode题目

注意事项

class Solution {
public:
    void reverseString(vector<char>& s) {
        for (int i = 0; i < s.size() / 2; i++) {
            char tmp = s[i];
            s[i] = s[s.size()-1-i];
            s[s.size()-1-i] = tmp;
        }  
    }
};

541. 反转字符串 II

LeetCode题目

class Solution {
public:
    string reverseStr(string s, int k) {
        int num = 0;
        while (num < s.size()) {
            if ((s.size() - num) > 2 * k) {
                reverse(s.begin()+num, s.begin()+num+k);
                num += 2 * k;
            }
            else if ((s.size() - num) >= k) {
                reverse(s.begin()+num, s.begin()+num+k);
                break;
            }
            else {
                reverse(s.begin()+num, s.end());
                break;
            }
        }
        return s;
    }
};

54.替换数字

题目

#include <iostream>
using namespace std;

int main() {
    string s;
    while(cin >> s) {
        int count = 0; // 统计数字的个数
        for (int i = 0; i < s.size(); i++) {
            if (s[i] >= '0' && s[i] <= '9') {
                count++;
            }
        }
        int pointer1 = s.size()-1, pointer2 = s.size()+5*count - 1; 
        s.resize(s.size()+5*count);
        while(pointer1 >= 0) {
            if (s[pointer1] >= '0' && s[pointer1] <= '9') {
                s[pointer2--] = 'r';
                s[pointer2--] = 'e';
                s[pointer2--] = 'b';
                s[pointer2--] = 'm';
                s[pointer2--] = 'u';
                s[pointer2--] = 'n';
            }
            else s[pointer2--] = s[pointer1];
            pointer1--;
        }
        cout << s << endl;
    }
}