给定两个数a和b,计算出1在a和b之间出现的次数

 1 #include<stdio.h>
 2 int main()
 3 {
 4     int a,b,i,cut;
 5     while(scanf("%d%d",&a,&b)!=EOF,(a||b))
 6     {
 7         if(a > b)
 8         {
 9             int t = a;
10             a = b;
11             b = t;
12         }
13         cut = 0;
14         for(i=a; i<=b; i++)
15         {
16             int ans = i;
17             while(ans > 0)
18             {
19                 if(ans%10 == 1)
20                     cut++;
21                 ans/=10;
22             }
23         }
24         printf("%dn",cut);
25     }
26     return 0;
27 }

 1 #include<iostream>
 2 #include<cstdio>
 3 using namespace std;
 4 int f(int n)
 5 {
 6     if(n < 1) return 0;
 7     int ans = 0;
 8     int   = 1;
 9     int round = n;
10     while(round > 0)
11     {
12         int weight = round%10;
13         round/=10;
14         ans+=round* ;
15         if(weight == 1)
16             ans+=(n% )+1;
17         else if(weight > 1)
18             ans+= ;
19          *=10;
20     }
21     return ans;
22 }
23 int main()
24 {
25     int a,b;
26     while(scanf("%d%d",&a,&b)!=EOF,(a||b))
27     {
28         if(a > b)
29         {
30             int t = a;
31             a = b;
32             b = t;
33         }
34         printf("%dn",f(b)-f(a-1));
35     }
36     return 0;
37 }