题解 | 字符串排序

#include <iostream>
#include <cctype>
#include <algorithm>
using namespace std;

int main() {
    string str, str1;
    getline(cin, str);
    for(const char& c: str) {
        if(isupper(c) || islower(c)) {
            str1 += c;
        }
    }
    stable_sort(str1.begin(), str1.end(), [](char a, char b) {
        char t1 = tolower(a);
        char t2 = tolower(b);
        return t1 < t2;
    });

    int slow = 0;
    for(int fast = 0; fast < str.size(); ++fast) {
        if(isalpha(str[fast])) {
            str[fast] = str1[slow++];
        }
    }
    cout << str << endl;

    return 0;
}