A1461 [2007 S2] 字符串的展开

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int p1, p2, p3;
    cin >> p1 >> p2 >> p3;
    string s;
    cin >> s;

    string out;
    int n = (int)s.size();
    for (int i = 0; i < n; i++) {
        bool expandable = false;
        if (s[i] == '-' && i > 0 && i + 1 < n) {
            char l = s[i - 1], r = s[i + 1];
            bool sameKind = (islower(l) && islower(r)) || (isdigit(l) && isdigit(r));
            expandable = sameKind && r > l;
        }
        if (!expandable) {
            // 不是可以展开的减号，原样输出
            out += s[i];
            continue;
        }
        // 减号两端的字符不变，只填充中间的字符
        string mid;
        for (char c = s[i - 1] + 1; c < s[i + 1]; c++) {
            char ch = c;
            if (p1 == 3) {
                ch = '*';
            } else if (p1 == 2 && isalpha(c)) {
                ch = (char)toupper(c);
            }
            for (int k = 0; k < p2; k++) mid += ch;
        }
        if (p3 == 2) reverse(mid.begin(), mid.end());
        out += mid;
    }

    cout << out << "\n";
    return 0;
}