在从1到n的正数中1出现的次数 【微软面试100题 第三十题】

#include <stdio.h>

int Sumls(int n)
{
int iCount=0,iFactor=1,iLowerNum=0,iCurrNum=0,iHigherNum=0;
while(n/iFactor!=0)
{
iLowerNum=n-(n/iFactor)*iFactor;
iCurrNum=(n/iFactor)%10;
iHigherNum=n/(iFactor*10);

switch(iCurrNum)
{
case 0:
iCount+=iHigherNum*iFactor;
break;
case 1:
iCount+=iHigherNum*iFactor+iLowerNum+1;
break;
default:
iCount+=(iHigherNum+1)*iFactor;
break;

}
iFactor*=10;

}
return iCount;
}

int main()
{
int i;

for(i = 1;i < 52;i++)
{
printf("%d里面含有 %d 个1\n",i,Sumls(i));
}

return 0;
}