Educational Codeforces Round 63 (Rated for Div. 2) (A,B,C)-蒲公英云

Educational Codeforces Round 63 (Rated for Div. 2) (A,B,C)

这次比赛很顺利的出了3个题，rating上涨了98，菜菜的我后面的不会了。

A - Reverse a Substring

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1e5+10;
const int MOD=1e9+7;
int main(){
    int n;
    scanf("%d\n",&n);
    string t;
    cin>>t;
    int l=0,r=0;
    for(int i=1;i<n;i++){
        if(t[i]<t[l]){
            r=i;
            break;
        }else l=i;
    }
    if(r!=0){
        printf("YES\n");
        printf("%d %d\n",l+1,r+1);
    }else{
        printf("NO\n");
    }
    return 0;
}

B - Game with Telephone Numbers

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1e5+10;
const int MOD=1e9+7;
int main(){
    int n,cnt=0;
    scanf("%d\n",&n);
    string t;
    cin>>t;
    n=n-10;
    for(int i=0;i<n;i++){
        if(t[i]=='8') cnt++;
    }
    if(cnt>=(n+1)/2){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
    return 0;
}

C - Alarm Clocks Everywhere

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1e5+10;
const int MOD=1e9+7;
ll gcd(ll a,ll b){
    if(b==0) return a;
    return gcd(b,a%b);
}
int main(){
    ll n,m;
    scanf("%lld%lld",&n,&m);
    ll x,p,a1,b1=-1,g,pre,b;
    scanf("%lld%lld",&a1,&b);
    g=b-a1;
    pre=b;
    for(ll i=3;i<=n;i++){
        scanf("%lld",&x);
        g=gcd(g,x-pre);
        pre=x;
    }
    for(ll i=1;i<=m;i++){
        scanf("%lld",&p);
        if(g%p==0) b1=i;
    }
    if(b1!=-1){
        printf("YES\n%lld %lld\n",a1,b1);
    }else{
        printf("NO\n");
    }
    return 0;
}