题解 | #字符串排序#

//设置大小写标记，然后稳定排序

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cctype>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <cstring>
#include <iomanip>
#include <sstream>

using namespace std;

#pragma warning(disable:4996)
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define repr(i, a, b) for(int i = a; i >= (b); --i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()

const int maxn = 10005;
const int INF = 0x3f3f3f3f;

struct node {
    char ch;
    bool isbig;
    node (char c, bool is) : ch(c), isbig(is) {}
};
bool cmp (node a, node b) {
    return a.ch < b.ch;
}
int main() {
    string str;
	while (getline(cin, str))
	{
		vector<node> t;
        rep(i, 0, sz(str)) {
            if (str[i] >= 'a' && str[i] <= 'z')
                t.push_back(node(str[i], false));
            else if (str[i] >= 'A' && str[i] <= 'Z')
                t.push_back(node(str[i] - 'A' + 'a', true));
        }
        stable_sort(t.begin(), t.end(), cmp);
        int idx = 0;
        rep(i, 0, sz(str)) {
            if (isalpha(str[i])) {
                if (t[idx].isbig)
                    cout << (char)(t[idx++].ch - 'a' + 'A');
                else
                    cout << (char)(t[idx++].ch);
            }
            else
                cout << str[i];
        }
        cout << endl;
	}
    return 0;
}