codeforce #629 div3

A. Divisibility Problem

Code

#include <bits/stdc++.h>
#define pii pair<int,int>
#define ll long long
using namespace std;
int main(){
	int t;
	cin>>t;
	while(t--){
		ll a,b;
		cin>>a>>b;
		if(a % b==0){
			cout<<"0"<<endl;
		}
		else if(a%b && a<b)
			cout<<b-a<<endl;
		else if(a==b)
			cout<<"0"<<endl;
		else{
			ll t=(a/b+1)*b;
			cout<<t-a<<endl;
		}
	}
}

B. K-th Beautiful String

Code

#include <bits/stdc++.h>
#define pii pair<int,int>
#define ll unsigned long long
using namespace std;
const int N=1e5+10;
ll st[N];
ll n,k;
unordered_map<ll,ll>h;
int find(int x){
	return lower_bound(st,st+n+1,x)-st;
}
int main(){
	st[1]=1;
	//h[1]=1;
	for(int i=2;i<N;i++){
		st[i]=(ll)(i+1)*i/2;
		h[st[i]]=i+1;
	}
	int t;
	cin>>t;
	while(t--) {
		cin >>n>>k;
		char str[N];
		int l;
		int r;
		if(k==1)
			l=1,r=2;
		else {
			int idx=find(k);
			l = st[idx];
			r = k - st[idx-1];
			l=h[l];
		}
		for(int i=1;i<=n;i++){
			if(i==l) str[i]='b';
			else if(i==r) str[i]='b';
			else str[i]='a';
		}
		reverse(str+1,str+1+n);
		for(int i=1;i<=n;i++)
			cout<<str[i];
		cout<<endl;
	}
}

C. Ternary XOR

Code

#include <bits/stdc++.h>
#define pii pair<int,int>
#define ll unsigned long long
using namespace std;
const int N=1e5+10;
char str[N],a[N],b[N];
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int t;
	cin>>t;
	while(t--){
		int n;
		cin>>n;
		cin>>str+1;
		bool left=0;
		for(int i=1;i<=n;i++) {
			if (!left) {
				if (str[i] == '2') {
					a[i] = '1';
					b[i] = '1';
				} else if (str[i] == '1') {
					a[i] = '1';
					b[i] = '0';
					left=1;
				} else {
					a[i] = '0';
					b[i] = '0';
				}
			}
			else {
				if(str[i]=='2'){
					a[i]='0';
					b[i]='2';
				}
				else if(str[i]=='1')
				{
					a[i]='0';
					b[i]='1';
				}
				else{
					a[i]='0';
					b[i]='0';
				}
			}
		}
		for(int i=1;i<=n;i++)
			cout<<a[i];
		cout<<endl;
		for(int i=1;i<=n;i++)
			cout<<b[i];
		cout<<endl;
	}
}

Code

Code

Code