BearAndSteadyGene_D.cpp

#include <bits/stdc++.h>
#define F first
#define S second
#define X real()
#define Y imag()
using namespace std;
typedef long long ll;
typedef long double ld;

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	string s;
	cin>>n>>s;
	int a=0;
	int c=0;
	int t=0;
	int g=0;
	for (int i=0;i<n;i++){
		if (s[i]=='A') a++;
		if (s[i]=='C') c++;
		if (s[i]=='T') t++;
		if (s[i]=='G') g++;
	}
	a-=n/4;
	c-=n/4;
	t-=n/4;
	g-=n/4;
	int i2=0;
	int ca=0;
	int cc=0;
	int ct=0;
	int cg=0;
	int v=n;
	for (int i=0;i<n;i++){
		while (i2<n&&(ca<a||cc<c||ct<t||cg<g)){
			if (s[i2]=='A') ca++;
			if (s[i2]=='C') cc++;
			if (s[i2]=='T') ct++;
			if (s[i2]=='G') cg++;
			i2++;
		}
		if (!(ca<a||cc<c||ct<t||cg<g)){
			v=min(v, i2-i);
		}
		if (s[i]=='A') ca--;
		if (s[i]=='C') cc--;
		if (s[i]=='T') ct--;
		if (s[i]=='G') cg--;
	}
	cout<<v<<endl;
}