P1098 [NOIP2007 提高组] 字符串的展开

注意三种情况：

 1.开头结尾的-，例：-abc-- 2.-两侧必须同为小写字母或同为数字 例;A-a 3.对数字不能进行大小写转换

#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <string>
#include <cmath>
#include <algorithm>
#define For(i, j, n) for (int i = j; i <= n; ++i)
using namespace std;

template <typename T>
inline T read()
{
    T x = 0;
    int f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x * f;
}

int p[4];
string _input, _ans;
bool in_pos[105];

string _produce(char left, char right)
{
    string res = "";
    bool flag = true;
    int _offset = 0;
    if (left == right || left > right)
    {
        res.append(1, '-');
        return res;
    }
    switch (p[1])
    {
    case 1:
        break;
    case 2:
        if(!isdigit(left))
            _offset = -32;
        break;
    default:;
    }
    if (flag)
    {
        for (char i = left + 1; i < right; i++)
            res.append(p[2], i + _offset);
    }
    if (p[1] == 3)
        res.replace(0, res.length(), string(res.length(), '*'));
    if (p[3] == 2)
        reverse(res.begin(), res.end());
    return res;
}

bool check(string str, int pos)
{
    if (pos < 1)
        return false;
    return (str[pos] == '-') && ((isdigit(str[pos - 1]) && isdigit(str[pos + 1])) | (isalpha(str[pos + 1]) && isalpha(str[pos - 1])));
}

int main()
{
    for (int i = 1; i <= 3; i++)
        cin >> p[i];
    cin >> _input;
    _ans = "";
    for (int i = 0; i < _input.length(); i++)
    {
        if (check(_input, i))
        {
            _ans += _produce(_input[i - 1], _input[i + 1]);
        }
        else
            _ans.append(1, _input[i]);
    }
    cout << _ans << endl;
    return 0;
}