Educational Codeforces Round 77 (Rated for Div. 2)

Educational Codeforces Round 77 (Rated for Div. 2)

A. Heating

• 思路：水题

• AC代码

---

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
 
ll mult_mod(ll x, ll y, ll mod){
    return (x * y - (ll)(x / (long double)mod * y + 1e-3) * mod + mod) % mod;
}
 
ll pow_mod(ll a, ll b, ll p){
    ll res = 1;
    while (b){
        if (b & 1)
            res = mult_mod(res, a, p);
        a = mult_mod(a, a, p);
        b >>= 1;
    }
    return res % p;
}
 
ll gcd(ll a, ll b){
    return b ? gcd(b, a % b) : a;
}
 
int n;
ll c, sum, ans;
 
int main(){
#ifndef ONLINE_JUDGE
    freopen("my_in.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    while (n -- ){
        ans = 0;
        cin >> c >> sum;
        if (sum % c == 0)
            ans = c * (sum / c) * (sum / c);
        else
            ans = (sum % c) * (sum / c + 1) * (sum / c + 1) + (c - sum % c) * (sum / c) * (sum / c); 
        cout << ans << "
";
    }
    return 0;
}

B. Obtain Two Zeroes

• 思路：讨论即可

• AC代码

---

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

ll mult_mod(ll x, ll y, ll mod){
    return (x * y - (ll)(x / (long double)mod * y + 1e-3) * mod + mod) % mod;
}

ll pow_mod(ll a, ll b, ll p){
    ll res = 1;
    while (b){
        if (b & 1)
            res = mult_mod(res, a, p);
        a = mult_mod(a, a, p);
        b >>= 1;
    }
    return res % p;
}

ll gcd(ll a, ll b){
    return b ? gcd(b, a % b) : a;
}

int t;
ll a, b;

int main(){
#ifndef ONLINE_JUDGE
    freopen("my_in.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> t;
    while (t -- ){
        cin >> a >> b;
        if (a == b){
            if (a % 3 == 0)
                cout << "YES
";
            else
                cout << "NO
";
            continue;
        }
        if (a > b)
            swap(a, b);
        if (a == 1){
            if (b == 2)
                cout << "YES
";
            else
                cout << "NO
";
            continue;
        }
        ll tmp = b - a;
        if (2 * a < b)
            cout << "NO
";
        else if (2 * a == b)
            cout << "YES
";
        else{
            a -= tmp;
            if (a % 3 == 0)
                cout << "YES
";
            else
                cout << "NO
";
        }
    }
    return 0;
}

C. Infinite Fence

• 思路：exgcd

• AC代码

---

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

ll mult_mod(ll x, ll y, ll mod){
    return (x * y - (ll)(x / (long double)mod * y + 1e-3) * mod + mod) % mod;
}

ll pow_mod(ll a, ll b, ll p){
    ll res = 1;
    while (b){
        if (b & 1)
            res = mult_mod(res, a, p);
        a = mult_mod(a, a, p);
        b >>= 1;
    }
    return res % p;
}

ll gcd(ll a, ll b){
    return b ? gcd(b, a % b) : a;
}

ll lcm(ll a, ll b){
    return a / gcd(a, b) * b;
}

int t;
ll r, b, k, lcm_, ans;

int main(){
#ifndef ONLINE_JUDGE
    freopen("my_in.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> t;
    while (t -- ){
        cin >> r >> b >> k;
        lcm_ = lcm(r, b);
        if (r > b)
            swap(r, b);
        ans = (lcm_ / r - 1 + lcm_ / b - 1) / (lcm_ / b);
        if (k > ans)
            cout << "OBEY
";
        else
            cout << "REBEL
";
    }
    return 0;
}

D. A Game with Traps

• 思路：二分+贪心 对于前面有陷阱的时候 考虑拆掉这个陷阱 拆完之后判断是否被覆盖来决定往后还是往回走 覆盖用前缀和 差分处理

• AC代码

---

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

ll mult_mod(ll x, ll y, ll mod){
    return (x * y - (ll)(x / (long double)mod * y + 1e-3) * mod + mod) % mod;
}

ll pow_mod(ll a, ll b, ll p){
    ll res = 1;
    while (b){
        if (b & 1)
            res = mult_mod(res, a, p);
        a = mult_mod(a, a, p);
        b >>= 1;
    }
    return res % p;
}

ll gcd(ll a, ll b){
    return b ? gcd(b, a % b) : a;
}

const int N = 2e5 + 10;

int m, n, k, t, l, r;
int a[N], cnt[N];

struct Trap{
    int l, r, d;
}trap[N];

inline bool cmp(const int &a, const int &b){
    return a > b;
}

inline bool check(int mid){
    int tot = 0;
    int low = a[mid];
    memset(cnt, 0, sizeof(cnt));
    for (int i = 1; i <= k; i ++ ){
        if (trap[i].d > low){
            cnt[trap[i].l] ++ ;
            cnt[trap[i].r + 1] -- ;
        }
    }
    for (int i = 1; i <= n + 1; i ++ )
        cnt[i] += cnt[i - 1];
    for (int i = 0; i <= n + 1; i ++ )
        tot += (cnt[i] >= 1);
    return tot * 2 + n + 1 <= t;
}

int main(){
#ifndef ONLINE_JUDGE
    freopen("my_in.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> m >> n >> k >> t;
    for (int i = 1; i <= m; i ++ )
        cin >> a[i];
    for (int i = 1; i <= k; i ++ )
        cin >> trap[i].l >> trap[i].r >> trap[i].d;
    sort(a + 1, a + m + 1, cmp);
    l = 0, r = m;
    while (l < r){
        int mid = (l + r + 1) >> 1;
        if (check(mid))
            l = mid;
        else
            r = mid - 1;
    }
    cout << l << "
";
    return 0;
}

E. Tournament

• 思路：贪心 在第i轮 前(2^i - 1)个人必定淘汰 每次选花费最小即可

• AC代码

---

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <string.h>
#include <string>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

ll mult_mod(ll x, ll y, ll mod){
    return (x * y - (ll)(x / (long double)mod * y + 1e-3) * mod + mod) % mod;
}

ll pow_mod(ll a, ll b, ll p){
    ll res = 1;
    while (b){
        if (b & 1)
            res = mult_mod(res, a, p);
        a = mult_mod(a, a, p);
        b >>= 1;
    }
    return res % p;
}

ll gcd(ll a, ll b){
    return b ? gcd(b, a % b) : a;
}

const int N = 3e5 + 10;

ll n, ans;
ll a[N];
multiset<int> ms;

int main(){
#ifndef ONLINE_JUDGE
    freopen("my_in.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i ++ )
        cin >> a[i];
    for (int i = n; i >= 1 && a[i] != -1; i -- ){
        ms.insert(a[i]);
        if (!(i & (i - 1))){
            ans += *ms.begin();
            ms.erase(ms.begin());
        }
    }
    cout << ans << "
";
    return 0;
}