Codeforces Educational Codeforces Round 54 (Rated for Div. 2)

A. Minimizing the String

#include<cstdio>
#include<cstring>
int main(){
	int n,i,f;
	char s[200005];
	scanf("%d%s",&n,s);
	f=n-1;
	for(int i=0;i<n-1;i++){
		if(s[i]>s[i+1]){
			f=i;
			break;
		}
		
	}
	for(int i=0;i<n;i++){
		if(i==f)
		continue;
		else printf("%c",s[i]);
	}
	printf("\n");
}

B. Divisor Subtraction

#include<cstdio>
int main(){
	long long n;
	scanf("%lld",&n);
	for(long long i=2;i*i<=n;i++){
		if(n%i==0){
			printf("%lld\n",(n-i)/2+1);
			return 0;
		}
	} 
	printf("1\n");
	return 0;
}

C. Meme Problem

#include<bits/stdc++.h>
#include<cmath>
using namespace std;
int main(){
	int T;
	scanf("%d",&T);
	while(T--){
		double d;
		scanf("%lf",&d);
		double D=d*d/4-d;
		if(D<0){
			printf("N\n");
		}
		else D=sqrt(D),printf("Y %.9lf %.9lf\n",d/2+D,d/2-D);
	}
}