Chewbaсca and Number------贪心

Luke Skywalker gave Chewbacca an integer number x. Chewbacca isn’t good at numbers but he loves inverting digits in them. Inverting digit t means replacing it with digit 9 - t.

Help Chewbacca to transform the initial number x to the minimum possible positive number by inverting some (possibly, zero) digits. The decimal representation of the final number shouldn’t start with a zero.

Input
The first line contains a single integer x (1 ≤ x ≤ 1018) — the number that Luke Skywalker gave to Chewbacca.

Output
Print the minimum possible positive number that Chewbacca can obtain after inverting some digits. The number shouldn’t contain leading zeroes.

Examples
Input
27
Output
22

Input
4545
Output
4444

题意

给你一个数字X，每一位子上的数字t都可以替换为9-t，让你输出最小的，不含有前导0的正整数，不能以0开头。

解题思路

这题的贪心思想很简单，根据样例都能看出来，就是每位上大于5的数t用9-t替换。但是，这题的坑特别多！！！！！！！好好读题，划重点：“输出最小的，不含有前导0的正整数”我当时就是没仔细读题被卡了好久…心态炸裂。这句话就是说第一位数是9的话不能转为零，就只能为9 ，就算x=9也是如此…
代码实现

#include <iostream>
#include <cstring>
#include<cstdio>
using namespace std;
int main() 
{
    char x[20];
    cin >> x;
    int len = strlen(x);//取出位数
    for (int i = 0; i < len; i++)
    {
            if (i == 0) //第一位
            {
                if (x[i] == '9')
                    cout << x[i];
                else if (x[i] >= '5')
                    cout << '9' - x[i];
                else cout << x[i];
            }
            else //剩余位
            {
                if (x[i] >= '5')
                    cout << '9' - x[i];
                else 
                    cout << x[i];
            }
    }
    cout << endl;
    return 0;
}