Codeforces Round #565 (Div. 3)

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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
    int q; cin >> q;
    while (q--) {
        ll n; cin >> n;
        ll ans = 0;
        while (n % 5 == 0) {
            n = n/5*4;
            ans++;
        }
        while (n % 3 == 0) {
            n = n/3*2;
            ans++;
        }
        while (n % 2 == 0) {
            n = n/2;
            ans++;
        }
        if (n != 1) ans = -1;
        cout << ans << endl;
    }
    return 0;
}

 

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1005;
map<int,int> mp;
int main() {
    int t; cin >> t;
    while (t--) {
        mp.clear();
        int n; cin >> n;
        int ans = 0;
        for (int i = 1; i <= n; ++i) {
            int x; cin >> x;
            if (x % 3 == 0) ans++;
            else mp[x%3]++;
        }
        if (mp[2] == mp[1]) ans += mp[1];
        else if (mp[2] > mp[1]) {
            ans += mp[1];
            mp[2] -= mp[1];
            ans += mp[2]/3;
        }
        else if (mp[1] > mp[2]) {
            ans += mp[2];
            mp[1] -= mp[2];
            ans += mp[1]/3;
        }
        cout << ans << endl;
    }
    return 0;
}

 

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
queue<int> que[10];
int main() {
    int n, good = 0;
    cin >> n;
    for (int i = 1; i <= n;++i) {
        int x; cin >> x;
        if (x == 4) que[1].push(i);
        else if (x == 8) que[2].push(i);
        else if (x == 15) que[3].push(i);
        else if (x == 16) que[4].push(i);
        else if (x == 23) que[5].push(i);
        else if (x == 42) que[6].push(i);
    }
    while (true) {
        int x = que[1].front();
        for (int i = 2; i <= 6; ++i) {
            while (que[i].front() < x && !que[i].empty()) {
                que[i].pop();
            }
            if (que[i].empty()) break;
            else if (i == 6 && !que[i].empty()) {
                good += 6;
                que[6].pop();
            }
            else {
                x = que[i].front();
                que[i].pop();
            }
        }
        if (que[1].empty()) break;
        else que[1].pop();
    }
    cout << n-good << endl;
    return 0;
}

 

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 4e5+5;
int b[maxn];
bool prime[2750131+5];
vector<int> ve, a;
map<int,int> mp;
bool cmp(int x, int y) {
    return x > y;
}
int main() {
    memset(prime,true,sizeof(prime));
    prime[0] = prime[1] = false;
    for (int i = 2; i <= 2750131; ++i) {
        if (prime[i] == false) continue;
        ve.push_back(i);
        for (int j = i*2; j <= 2750131; j+=i) {
            prime[j] = false;
        }
    }
    /*
    for (int i = 1; i <= 100; ++i) {
        cout << "i: " << i << " prime: " << prime[i] << endl; 
    }
    */
    // cout << lower_bound(ve.begin(),ve.end(),5)-ve.begin()+1 << endl;
    int n; scanf("%d",&n);
    for (int i = 1; i <= 2*n; ++i) {
        scanf("%d",&b[i]);
        mp[b[i]]++;
    }
    sort(b+1,b+1+2*n,cmp);
    // for (int i = 1; i <= 2*n; ++i) cout << b[i] << endl;
    for (int i = 1; i <= 2*n; ++i) {
        if (mp[b[i]] == 0) continue;
        if (prime[b[i]] == true) {  // 如果是质数
            int ans = lower_bound(ve.begin(),ve.end(),b[i])-ve.begin()+1;  // 搜索是第几个质数 
            if (prime[ans] == true) {
                mp[ans]--; mp[b[i]]--;
                a.push_back(ans);
                continue;
            }
        }
        
        int ans = 1;
        for (int j = 2; j*j <= b[i]; ++j) {  // 搜索最大除数 
            if (b[i] % j == 0) ans = max(ans,b[i]/j);
        }
        mp[ans]--; mp[b[i]]--;
        a.push_back(b[i]);
    }
    printf("%d",a[0]);
    for (int i = 1; i < a.size(); ++i) {
        printf(" %d",a[i]);
    }
    printf("\n");
    return 0;
}

 

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5+5;
vector<int> ve[maxn];
set<int> se1, se2;
bool vis[maxn];
void dfs(int u, int fa, bool odd) {
    if (odd == true) se1.insert(u);
    else se2.insert(u);
    for (int i = 0; i < ve[u].size(); ++i) {
        int to = ve[u][i];
        if (to == fa) continue;
        if (vis[to] == true) continue;
        vis[to] = true;
        dfs(to,u,odd^1);
    }
}
int main() {
    int t; scanf("%d",&t);
    while (t--) {
        memset(vis,false,sizeof(vis));
        se1.clear(); se2.clear();
        int n, m; scanf("%d%d",&n,&m);
        for (int i = 1; i <= n; ++i) {
            ve[i].clear();
        }
        for (int i = 1; i <= m; ++i) {
            int u, v; scanf("%d%d",&u,&v);
            ve[u].push_back(v);
            ve[v].push_back(u);            
        }
        vis[1] = true;
        dfs(1,-1,true);
        if (se1.size() <= se2.size()) {
            printf("%d\n",se1.size());
            for (set<int>::iterator iter = se1.begin(); iter != se1.end(); ++iter) {
                if (iter == se1.begin()) printf("%d",*iter);
                else printf(" %d",*iter);
            }
            putchar('\n');
        }
        else {
            printf("%d\n",se2.size());
            for (set<int>::iterator iter = se2.begin(); iter != se2.end(); ++iter) {
                if (iter == se2.begin()) printf("%d",*iter);
                else printf(" %d",*iter);
            }
            putchar('\n');
        }
    }
    return 0;
}