HDU 5059 help him (simulation)

Question link: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 5059

Problem descriptionas you know, when you want to hack someone's program, you must submit your test data. however sometimes you will submit invalid data, so we need a data Checker to check your data. now small W has prepared a problem for BC, but he is too busy to write the data checker. please help him to write a data check which judges whether the input is an integer ranged from A to B (random SIVE ).
Note: A string represents a valid integer when it follows below rules.
1. When it represents a non-negative integer, it contains only digits without leading zeros.
2. When it represents a negative integer, it contains exact one negative sign ('-') followed by digits without leading zeros and there are no characters before '-'.
3. Otherwise it is not a valid integer.
Inputmulti test cases (about 100), every case occupies two lines, the first line contain a string which represents the input string, then second line contains a and B separated by space. process to the end of file.

Length of string is no more than 100.
The string may contain in any characters other than '\ n',' \ R '.
-1000000000 ≤ A ≤ B ≤ 1000000000
Outputfor each case output "yes" (without quote) when the string is an integer ranged from A to B, otherwise output "no" (without quote ).
Sample Input

10-100 1001a0-100 100

Sample output

YESNO

Sourcebestcoder round #12

Question:

Given a string, if the string is an integer and the integer is within the range of [a, B], yes is output and no is output from other strings.

This string is an integer condition:

1. If it is a positive integer, it only contains numbers whose leading value is not 0 (there is no zero before this number ).

2. If it is a negative integer, it only contains a '-' symbol, and no leading 0 is given.

3. It is not illegal.

PS:

Note the leading zero and invalid characters!

The Code is as follows:

#include <cstdio>#include <cstring>const int maxn = 517;char str[maxn], ans[maxn];typedef __int64 LL;int flag = 0, mark = 0;LL ATOL(char s[]){    int len = strlen(s);    LL tt = 0;    int i = 0;    if(s[0] == '-')//负号    {        mark = 1;        i++;    }    for(; i < len; i++)    {        if(s[i]<'0' || s[i]>'9')//非法字符        {            flag = 1;            break;        }        if(tt == 0 && s[i]=='0' && len > 1)        {            //前导零            flag = 1;            break;        }        tt = tt*10+s[i]-'0';    }    return tt;}int main(){    LL a, b;    LL tt;    while (gets(str))    {        flag = 0;        mark = 0;        scanf("%I64d%I64d", &a, &b);        getchar();        int len = strlen(str);        if (len >= 13 || len == 0)        {            printf("NO\n");            continue;        }        //tt = atol(str);        tt = ATOL(str);        //printf("tt:: %I64d\n",tt);        if(mark && tt == 0)//-0        {            printf("NO\n");            continue;        }        if(flag)        {            printf("NO\n");            continue;        }        if(mark)//负数            tt = -tt;        if (a <= tt && tt <= b)            printf("YES\n");        else            printf("NO\n");    }    return 0;}

HDU 5059 help him (simulation)