洛谷P1098字符串的展開

題目
字符串的題坑點一如既往的多，每次都很難考慮周全

#include <iostream>
#include <string>
#include <cmath>
#include <map>
#include <cstring>
#include <algorithm>
using namespace std;

bool IsDigit(char ch) 
{
    return (ch >= '0' && ch <= '9') ? true : false;
}
bool IsCharacter(char ch)
{
    return (ch >= 'a' && ch <= 'z') ? true : false;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int p1, p2, p3;
    cin >> p1 >> p2 >> p3;
    string str;
    cin >> str;
    for (int i = 1; i < str.size() - 1; i++) {
        if (str[i] == '-') {
            if ( (IsDigit(str[i - 1]) && IsDigit(str[i + 1])) || (IsCharacter(str[i - 1]) && IsCharacter(str[i + 1])) ) {
                if (str[i - 1] >= str[i + 1]) {
                    continue;
                }
                else if (str[i - 1] + 1 == str[i + 1]) {
                    str.erase(i, 1);
                    i--;
                }
                else {  
                    char tmp[1000];
                    int cnt = 0;
                    for (int j = str[i - 1] + 1; j < str[i + 1]; j++) {
                        char ch = j;
                        if (p1 == 2 && str[i - 1] > '9') {
                            ch -= 32;
                        }
                        else if (p1 == 3) {
                            ch = '*';
                        }
                        
                        for (int k = 0; k < p2; k++) {
                            tmp[cnt++] = ch;    
                        }
                    }
                    if (p3 == 2) {
                        reverse(tmp, tmp + cnt);
                    }
                    str.erase(i, 1);
                    str.insert(i, tmp, cnt);
                }
            }
        }
    }
    cout << str << endl;
    return 0;
}