pta 逆序



int reverse( int number ){
	int sum=0,t,flag;
	if(number<0){
		flag=-1;
		number=-number;
	}
	
	else
	  flag=1;
	while(number!=0){
	    sum=sum*10+number%10;
		number=number/10;
	}
	sum=sum*flag;
}
//这个在测试时无法通过
//错误点：没有return 
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int reverse(int number){
   int res = 0;
   while(number != 0){
      res = res * 10 + number % 10;
      number = number/10;
   }
   return res;
}

//这个是正确答案


---------------------------------------------------------

int reverse( int number ){
	int count=1,n,r=0,flag=1;
	if(number<0){
		flag=-1;
		number=-number;
	}
		n=number;
	while(n){
		count=10*count;
		n=n/10;
	} 
	while(number){ 
		r=r+(number%10)*count;
		number=number/10;
		count=count/10;
	}
	r=r*flag;
	return r;
}

//测试时无法通过
//错误点：在第一个while后count值应除以10
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注意点：
1.printf("%d",-123%10);结果是：-3
所以此题没有必要放flag对负号进行处理。