#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main()
{
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int n,m;
cin>>n>>m;
string t,s="abc";
cin>>t;
vector<vector<int> >pre(6,vector<int>(n+1));
int cnt=0;
do
{
for(int i=1;i<=n;i++)
{
pre[cnt][i] = pre[cnt][i-1] + (s[(i-1)%3]==t[i-1]?0:1);//1:0
}
cnt++;
}while(next_permutation(s.begin(),s.end()));
while(m--)
{
int l,r;
cin>>l>>r;
int ans=1e9;
for(int i=0;i<6;i++)ans=min(ans,pre[i][r]-pre[i][l-1]);
cout<<ans<<endl;
}
return 0;
}
CF 1555 D. Say No to Palindromes(构造)
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转载自blog.csdn.net/Ambrumf/article/details/120846804
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