Educational Codeforces Round 98 (Rated for Div. 2)

A - Robot Program

直接跳

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map> 
#include <stack>
#include <sstream>
#include <set>
// #pragma GCC optimize(2)

//#define int long long
#define ls u<<1
#define rs u<<1|1
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define rush() int T;scanf("%d",&T);for(int Ti=1;Ti<=T;++Ti)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mm(i,v) memset(i,v,sizeof i);
#define mp(a, b) make_pair(a, b)
#define pi acos(-1)
#define fi first
#define se second

using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int, int > PII;
priority_queue< PII, vector<PII>, greater<PII> > que;
stringstream ssin; //  ssin << string   while ( ssin >> int)
const ll LINF = 0x7fffffffffffffffll;

const int N = 4e5 + 5, M = 4e5 + 5, mod = 1e9 + 7, INF = 0x3f3f3f3f;
int _, x, y, ans;

inline ll read() {
    char c=getchar();ll x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
    return x*f;
}


int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif

    _ = read();
    while (_--) {
        ans = 0;
        x = read(); y = read();
        ans += min(x, y) * 2;
        int t = min(x, y);
        x -= t; y -= t;
        if (x) {
            ans += 2 * x - 1;
        } else if (y) {
            ans += 2 * y - 1;
        }
        cout << ans << '
';
    }
    

    // #ifndef ONLINE_JUDGE
    //     system("pause");
    // #endif
}

B - Toy Blocks

比较一下最大值和剩下n - 1个即可

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map> 
#include <stack>
#include <sstream>
#include <set>
// #pragma GCC optimize(2)

//#define int long long
#define ls u<<1
#define rs u<<1|1
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define rush() int T;scanf("%d",&T);for(int Ti=1;Ti<=T;++Ti)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mm(i,v) memset(i,v,sizeof i);
#define mp(a, b) make_pair(a, b)
#define pi acos(-1)
#define fi first
#define se second

using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int, int > PII;
priority_queue< PII, vector<PII>, greater<PII> > que;
stringstream ssin; //  ssin << string   while ( ssin >> int)
const ll LINF = 0x7fffffffffffffffll;

const int N = 4e5 + 5, M = 4e5 + 5, mod = 1e9 + 7, INF = 0x3f3f3f3f;
ll _, n, sum, max1, max2;
ll a[N];

inline ll read() {
    char c=getchar();ll x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
    return x*f;
}


int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    
    _ = read();
    while (_--) {
        n = read();
        sum = 0; max1 = 0; max2 = 0;
        rep(i, 1, n) {
            a[i] = read();
            if (a[i] > max1) {
                max2 = max1; max1 = a[i];
            } else if (a[i] == max1) {
                max2 = a[i];
            }
            sum += a[i];
        }
        ll ans = 0;
        ll tmp = max1 * (n - 1);
        if (sum >= tmp)
        {
            printf("%lld
",sum%(n-1)==0? 0: (n-1)-sum%(n-1));
        }
        else
            printf("%lld
",tmp-sum);
    }

    // #ifndef ONLINE_JUDGE
    //     system("pause");
    // #endif
}

C - Two Brackets

括号匹配

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map> 
#include <stack>
#include <sstream>
#include <set>
// #pragma GCC optimize(2)

//#define int long long
#define ls u<<1
#define rs u<<1|1
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define rush() int T;scanf("%d",&T);for(int Ti=1;Ti<=T;++Ti)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mm(i,v) memset(i,v,sizeof i);
#define mp(a, b) make_pair(a, b)
#define pi acos(-1)
#define fi first
#define se second

using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int, int > PII;
priority_queue< PII, vector<PII>, greater<PII> > que;
stringstream ssin; //  ssin << string   while ( ssin >> int)
const ll LINF = 0x7fffffffffffffffll;

const int N = 4e5 + 5, M = 4e5 + 5, mod = 1e9 + 7, INF = 0x3f3f3f3f;
int _;
char s[N];
stack<char>s1, s2;

inline ll read() {
    char c=getchar();ll x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
    return x*f;
}


int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    
    _ = read();
    while (_--) {
        while (!s1.empty()) s1.pop();
        while (!s2.empty()) s2.pop();
        scanf("%s", s + 1);
        int len = strlen(s + 1);
        int ans = 0;
        rep(i, 1, len) {
            char x = s[i];
            if (x == '(') s1.push(x);
            if (x == '[') s2.push(x);

            if (x == ')') {
                if (s1.empty()) {
                    s1.push(x);
                    continue;
                }
                char y = s1.top();
                if (y == '(') {
                    ans++;
                    s1.pop();
                } else s1.push(x);
            }

            if (x == ']') {
                if (s2.empty()) {
                    s2.push(x);
                    continue;
                }
                char y = s2.top();
                if (y == '[') {
                    ans++;
                    s2.pop();
                } else s2.push(x);
            }
        }
        cout << ans << '
';
    }

    // #ifndef ONLINE_JUDGE
    //     system("pause");
    // #endif
}

D - Radio Towers

分子斐波那契，分母2的幂次

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map> 
#include <stack>
#include <sstream>
#include <set>
// #pragma GCC optimize(2)

//#define int long long
#define ls u<<1
#define rs u<<1|1
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define rush() int T;scanf("%d",&T);for(int Ti=1;Ti<=T;++Ti)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mm(i,v) memset(i,v,sizeof i);
#define mp(a, b) make_pair(a, b)
#define pi acos(-1)
#define fi first
#define se second

using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int, int > PII;
priority_queue< PII, vector<PII>, greater<PII> > que;
stringstream ssin; //  ssin << string   while ( ssin >> int)
const ll LINF = 0x7fffffffffffffffll;

const int N = 4e5 + 5, M = 4e5 + 5, mod = 998244353, INF = 0x3f3f3f3f;
ll n;
ll fab[N], fac[N];

inline ll read() {
    char c=getchar();ll x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
    return x*f;
}

ll qp(ll a, ll b) {
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans = ans * a % mod;
        }
        a = a * a % mod;
        b = b / 2;
    }
    return ans % mod;
}

int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    
    n = read();
    fab[1] = 1; fab[2] = 1;
    fac[0] = 1; fac[1] = 2; fac[2] = 4;
    for (int i = 3; i <= n; ++i) {
        fac[i] = fac[i - 1] * 2 % mod;
        fab[i] = fab[i - 1] + fab[i - 2];
        fab[i] %= mod;
    }

    // cout << fab[n - 1] << '
';
    // cout << fac[n] << '
';

    cout << fab[n] % mod * qp(fac[n], mod - 2) % mod << '
';

    // #ifndef ONLINE_JUDGE
    //     system("pause");
    // #endif
}

E - Two Editorials

先固定第一个k1，枚举所有区间，可以通过二维差分约束O(1)预处理出第二个范围k2在每个位置的贡献，具体如下

add(L + len, 1);

add(R - len + 1 + k, 1);

add(min(L + k, R + 1), -1);

add(max(L + r, R + 1), -1);

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map> 
#include <stack>
#include <sstream>
#include <set>
// #pragma GCC optimize(2)

//#define int long long
#define ls u<<1
#define rs u<<1|1
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define REP(i,a,n) for(int i=a;i>=n;--i)
#define rush() int T;scanf("%d",&T);for(int Ti=1;Ti<=T;++Ti)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mm(i,v) memset(i,v,sizeof i);
#define mp(a, b) make_pair(a, b)
#define pi acos(-1)
#define fi first
#define se second

using namespace std;
typedef long long ll;
typedef double db;
typedef pair<int, int > PII;
priority_queue< PII, vector<PII>, greater<PII> > que;
stringstream ssin; //  ssin << string   while ( ssin >> int)
const ll LINF = 0x7fffffffffffffffll;

const int N = 4e5 + 5, M = 4e5 + 5, mod = 1e9 + 7, INF = 0x3f3f3f3f;
int n, m, k, ans;
int d2[N];
PII a[N];

inline ll read() {
    char c=getchar();ll x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1; c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0'; c=getchar();}
    return x*f;
}

int f(int l1, int r1, int l2, int r2) {
    if (l1 > l2) {
        swap(l1, l2);
        swap(r1, r2);
    }
    if (r1 < l2) return 0;
    return min(r1, r2) - l2 + 1;
}

void add(int x, int v) {
    d2[x] += v;
}

int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    n = read(); m = read(); k = read();
    rep(i, 1, m) a[i].fi = read(), a[i].se = read();
    

    rep(i, k, n) {

        rep(j, 0, n) d2[j] = 0;
        int now = 0, res = 0;

        rep(j, 1, m) {
            int L = a[j].fi, R = a[j].se;
            now = f(L, R, i - k + 1, i);
            res += now;

            if (now == k || now == R - L + 1) continue;

            add(L + now, 1);
            add(R - now + 1 + k, 1);
            add(min(L + k, R + 1), -1);
            add(max(L + k, R + 1), -1);

        }
        rep(j, 1, n) {
            d2[j] += d2[j - 1];
        }
        rep(j, 1, n) {
            d2[j] += d2[j - 1];
            if (j >= k) ans = max(ans, res + d2[j]);
        }
    }           
    cout << ans << '
';

    // #ifndef ONLINE_JUDGE
    //     system("pause");
    // #endif
}