2019江西省省赛

 

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
char c[1000];
ll l,k1,k2,k3,k4,k,kk,d;

int main(){
    while (~scanf("%lld",&l)) {
        scanf("%s", c);
        k1=k2=k3=k4=0;
        for (int i = 0; i < l; i++) {
            if (c[i] == 'a') k1++;
            if (c[i] == 'v') k2++;
            if (c[i] == 'i') k3++;
            if (c[i] == 'n') k4++;
        }
        k = k2 * k1 * k3 * k4;
        kk = l * l * l * l;
        if (k == 0) {
            printf("0/1
");
            continue;
        }
        d = __gcd(k, kk);
        k = k / d;
        kk = kk / d;
        printf("%lld/%lld
", k, kk);
    }
}

#include <bits/stdc++.h>
using namespace std;

int a[2000],b[2000],c[2000],d[2000],t,f,n,m;
int main() {
    while (~scanf("%d%d",&n,&m)) {
        for (int i = 1; i <= n; i++) {
            scanf("%d", &a[i]);
        }
        for (int i = 1; i <= m; i++) {
            scanf("%d", &b[i]);
        }
        t=0;
        while (1) {
            memset(c,0, sizeof(c));
            memset(d,0, sizeof(d));
            for (int i = 1; i <= n; i++) {
                c[a[i]] = 1;
            }
            for (int i = 1; i <= m; i++) {
                d[b[i] + t] = 1;
            }
            f=0;
            for (int i=1;i<=1000;i++){
                if (c[i]&&d[i]==1){
                    f=1;
                    break;
                }
            }
            if (!f){
                printf("%d
",t);
                break;
            }
            t++;
        }
    }
}

#include <bits/stdc++.h>
using namespace std;
const int mod = 1000000007;
long long quickpow(long long a, long long b) {
    if (b < 0) return 0;
    long long ret = 1;
    a %= mod;
    while(b) {
        if (b & 1) ret = (ret * a) % mod;
        b >>= 1;
        a = (a * a) % mod;
    }
    return ret;
}
long long inv(long long a) {
    return quickpow(a, mod - 2);
}
int main() {
    long long  n;
    scanf("%lld",&n);
    long long ans=((n+1)*inv(2*n))%mod;
    printf("%lld
",ans);
    return 0;
}

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
ll n,b[1000],a[2000],m,lcm,x[2000],k,sum;

ll gcd(ll a,ll b){
    if (!b){
        return a;
    }
    return gcd(b,a%b);
}
int main() {
    while (~scanf("%lld%lld", &n,&m)) {
        for (int i=1;i<=n;i++){
            scanf("%lld",&a[i]);
            b[a[i]]++;
        }
        lcm=1;
        for (int i=1;i<=10;i++){
            if (b[i]){
                lcm=i/gcd(i,lcm)*lcm;
            }
        }
        for (int i=1;i<=n;i++){
            x[i]=lcm/a[i];
            sum+=x[i];
        }
        if (m%sum==0){
            k=m/sum;
            printf("Yes
");
            for (int i=1;i<=n;i++){
                printf("%lld",x[i]*k);
                if (i==n){
                    printf("
");
                }else{
                    printf(" ");
                }
            }
        }else{
            printf("No
");
        }
    }
}

#include<bits/stdc++.h>
using namespace std;

int main()
{
    int x,y;
    scanf("%d%d",&x,&y);
    printf("%d
",(x*x-y*y)/4);
}

#include <bits/stdc++.h>
using namespace std;
char c[100];
double ans;
int n,l;
int main() {
    while (~scanf("%d", &n)) {
        ans=0;
        for (int i = 1; i <= n; i++) {
            scanf("%s", &c);
            l = strlen(c);
            if (c[l - 1] < '5') {
                ans -= 0.001 * (c[l - 1] - '0');
            } else {
                ans += (10 - (c[l - 1] - '0')) * 0.001;
            }
        }
        printf("%.3lf
", ans);
    }
}

#include<bits/stdc++.h>

using namespace std;
vector<int>a[105];
int ans,n,c,x,s1,s2,k1,k2,sum,tmp;
int main() {
    scanf("%d%d", &n, &c);
    for (int i = 1; i <= n; i++) {
        scanf("%d", &x);
        a[x].push_back(i);
    }
    for (int i = 1; i <= c; i++) {
        for (int j = 1; j <= c; j++) {
            if (i != j) {
                s1 = a[i].size();
                s2 = a[j].size();
                k1 = k2 = sum = tmp = 0;
                while (1) {
                    while (k1 < s1 && a[i][k1] < tmp) {
                        k1++;
                    }
                    if (k1 == s1) {
                        break;
                    }
                    tmp = a[i][k1];
                    sum++;
                    while (k2 < s2 && a[j][k2] < tmp) {
                        k2++;
                    }
                    if (k2 == s2) {
                        break;
                    }
                    tmp = a[j][k2];
                    sum++;
                }
                ans = max(ans, sum);
            }
        }
    }
    printf("%d
", ans);
}