UVA 10299 - Relatives Solution

#include<cstdio>
#include<cmath>
using namespace std;

int phi(int n)
{
    int res=n;
    for (int i=2;i*i<=n;i++)
    {
        if (n%i==0)
        {
            while (n%i==0) n/=i;
            res-=res/i;
        }
    }
    if (n>1) res-=res/n;
    return res;
}
int main ()
{
    int n;
    while (scanf("%d",&n)==1)
    {
        if (n==0) return 0;
        if (n==1) printf("0\n");
        else printf("%d\n",phi(n));
    }

    return 0;
}

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Codeforces 697A - Pineapple Incident

#include<cstdio>
#include<cmath>
using namespace std;
int main()
{
    int t,s,x;
    scanf("%d%d%d",&t,&s,&x);
    if (x>=t &&( (x-t)%s==0 || (x-t-1!=0 && (x-t-1)%s==0))) printf("YES\n");
    else printf("NO\n");
    return 0;
}

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Codeforces 689A - Mike and Cellphone

#include<cstdio>
#include<cstring>
using namespace std;
int main()
{
    int n,l,r,u,d;
    l=r=u=d=0;
    scanf("%d",&n);
    getchar();
    char s[11];
    scanf("%s",s);
    for (int i=0;i<n;i++){
        int a=s[i]-'0';
        if (a==1 || a==4||a==7||a==0) l=1;
        if (a==3 || a==6||a==9||a==0) r=1;
        if (a==1 || a==2||a==3) u=1;
        if (a==7 || a==0||a==9) d=1;
    }
    if (l && r && u && d) printf("YES\n");
    else printf("NO\n");
    return 0;
}

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Codeforces 688B - Lovely Palindromes

#include<cstdio>
#include<cstring>
using namespace std;
int main()
{
    char s[100005];
    gets(s);
    printf("%s",s);
    for (int i=strlen(s)-1;i>-1;i--) printf("%c",s[i]);
    printf("\n");
    return 0;
}

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Codeforces 698A - Vacations

#include<cstdio>
using namespace std;
int main()
{
    int n;
    scanf("%d",&n);
    int a[n];
    for (int i=0;i<n;i++)
        scanf("%d",&a[i]);
    int rest=0;
    int p=0;
    for (int i=0;i<n;i++)
    {
        if (a[i]==0){
            rest++;
            p=0;
        }
        else if (!p){
            p=a[i];
        }
        else if (p==3){
                p=a[i];
        }
        else if(p==2 && a[i]!=2 ){
            p=1;
        }
        else if(p==2 && a[i]==2 ){
            p=0;
            rest++;
        }
        else if(p==1 && a[i]!=1 ){
            p=2;
        }
        else if(p==1 && a[i]==1 ){
            p=0;
            rest++;
        }
    }
    printf("%d\n",rest);

    return 0;
}

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Codeforces : 702A - Maximum Increase

#include<cstdio>
using namespace std;
int main()
{
    int n;
    scanf("%d",&n);
    int a[n];
    for (int i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    int max=1,cur=1;
    for (int i=1;i<n;i++){
        if (a[i]>a[i-1]){
            cur++;
        }
        else{
            if (max<cur) max=cur;
            cur=1;
        }
    }
    if (max<cur) max=cur;
    printf("%d\n",max);
    return 0;
}

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Codeforces 703B Mishka and trip

#include<cstdio>
#include<string.h>
using namespace std;
typedef long long unsigned int llu;

int main()
{
    int n,k;
    while (scanf("%d%d",&n,&k)!=EOF)
    {
        int c[n+1];
        int d[k];
        bool cap[n+1];
        memset(cap,false,sizeof(cap));
        llu sum=0,ans=0;
        for (int i=1;i<=n;i++)
        {
            scanf("%d",&c[i]);
            sum+=c[i];
        }
        for (int i=0;i<k;i++)
        {
            scanf("%d",&d[i]);
            cap[d[i]]=true;
        }
        for (int i=0;i<k;i++)
        {
            ans+=c[d[i]]*(sum-c[d[i]]);
            sum-=c[d[i]];
        }
        for (int i=1;i<n;i++)
            if (!cap[i] && !cap[i+1])
                ans+=c[i]*c[i+1];
        if (!cap[1] && !cap[n])
            ans+=c[1]*c[n];
        printf("%llu\n",ans);
    }
    return 0;
}

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