题目地址：http://codeforces.com/gym/100819/attachments
题目：
Define the complexity of a string to be the number of distinct letters in it. For example, the stringstring has complexity 6 and the string letter has complexity 4.
You like strings which have complexity either 1 or 2. Your friend has given you a string andyou want to turn it into a string that you like. You have a magic eraser which will delete one letterfrom any string. Compute the minimum number of times you will need to use the eraser to turnthe string into a string with complexity at most 2.
Input
The input consists of a single line that contains a single string of at most 100 lowercase ASCIIletters (‘a’–‘z’).
Output
Print, on a single line, the minimum number of times you need to use the eraser.
思路：
没啥思路，水题。给你一堆字母，不管它有几种字母，要把它减少到只有两种，问最少删掉几个字母。
于是就用set统计个数，用数组记录每个字母的个数，贪心一下。
代码：
#include<iostream>
#include<string>
#include<cstring>
#include<set>
#include<algorithm>
using namespace std;
bool cmp(int a,int b)
{
return a>b;
}
int main()
{
string a;
while(cin>>a)
{
set<char>s;
int b[150];
memset(b,0,sizeof(b));
int c=a.length();
int i;
for(i=0;i<c;i++)
{
s.insert(a[i]);
b[a[i]]++;
}
if(s.size()<=2)cout<<0<<endl;
else
{
//int t=s.size()-2;
sort(b,b+150,cmp);
int sum=0;
for(i=s.size();i>=2;i--)
{
sum=sum+b[i];
}
cout<<sum<<endl;
}
}
return 0;
}