HDU 5059 Help him（字符串 筛选数字 模拟）（atoi sprintf 函数）

Help him

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 2674    Accepted Submission(s): 550


Problem Description

As 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 (inclusive).

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.

 

Input

Multi 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 any characters other than '\n','\r'.

-1000000000≤a≤b≤1000000000

 

Output

For 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
-100 100
1a0
-100 100

 

Sample Output

YES
NO

 

Source

BestCoder Round #12

 

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题目大意：

给定一个字符串，字符串可以包括除'\n'，'\r'以外的任何字符。在给定一个区间，判断该字符串是否是正确的数字类型（不包含前导0，除了负号以外不包括任何非数字元素，-0判错，不能有空格）。

解题思路：

本来想着只是一个简单模拟的过程，不过写出来之后自己能想到的测试数据都能过，交上去之后却总是WA。最后通过看一些大神的博客才知道原来还有atoll，和sprintf这种好用的函数。用gets()输入，记得将a，b后面的回车用getchar（）吃掉。将接收的字符串用atoll()函数先转为数字，这里可以遇到不合法的字符就会终止，然后再用sprintf()函数将其转化为字符串，最后用strcmp()函数进行比较是否相等，且在[a,b]范围内，则输出“YES”，反之为"NO".两种写法详见code。

简单代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <stdlib.h>
using namespace std;

const int MAXN = 100+10;
char str[MAXN],cp[MAXN];
int k,a,b;

int main(){
//freopen("input.txt","r",stdin);
while(gets(str)){
scanf("%d%d",&a,&b);
getchar();
int x=atoll(str);
sprintf(cp,"%d",x);
if(strcmp(str,cp)==0 && x>=a && x<=b) puts("YES");
else puts("NO");
}
return 0;
}

网上找的直接模拟的代码：

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

#define ll __int64
const int MAXN = 100+10;
char str[MAXN],s[MAXN];
ll a,b,ans;

bool judge(char *s){
int len=strlen(s);
int id=0,sy=0;
ans=0;
if(s[0]=='-'){
++id;
sy=1;
}
if(len-id>12 || len==0) return false;
if(len==1 && s[0]=='-') return false;
if(s[id]<'0' || s[id]>'9') return false;
if(sy){
if(s[1]=='0') return false;
for(int i=id;i<len;++i){
if(s[i]<'0' || s[i]>'9') return false;
ans=ans*10+s[i]-'0';
}
ans=-ans;
if(ans>=a && ans<=b) return true;
}
else{
if(s[0]=='0' && len>1) return false;
for(int i=id;i<len;++i){
if(s[i]<'0' || s[i]>'9') return false;
ans=ans*10+s[i]-'0';
}
if(ans>=a && ans<=b) return true;
}
return false;
}

int main(){
//freopen("input.txt","r",stdin);
while(gets(str)){
scanf("%I64d %I64d",&a,&b);
getchar();
if(judge(str)) puts("YES");
else puts("NO");
}
return 0;
}