字符串

https://codeforces.com/gym/580226/problem/A

#include<bits/stdc++.h>
#define lc p<<1
#define rc p<<1|1
#define INF 2e9
using namespace std;

#define endl '\n'
using ll = long long;
using pii = pair<ll, ll>;
const double PI = acos(-1);
const int N=1e4+10;

void solve(){
	ll n,a,b;cin>>n>>a>>b;
	string s;cin>>s;
	s=" "+s;
	ll ans=0;
	ans+=a*n;
	if(b>=0){
		ans+=b*n;
	}
	else{
		ll cnt0=0,cnt1=0;
		for(int i=1;i<=n;i++)
		{
			if(s[i]!=s[i-1]&&s[i]=='0')
				cnt0++;
			if(s[i]!=s[i-1]&&s[i]=='1')
				cnt1++;
		}
		ans+=(min(cnt0,cnt1)+1)*b;
	}
	cout<<ans<<endl;
}


int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr), cout.tie(nullptr);
	
	int T = 1;
	cin>>T;
	while (T--) {
		solve();
	}
	
	return 0;
}