AtCoder Beginning Contest 137

好久没打过abc了。

题目链接：https://atcoder.jp/contests/abc137/tasks_print

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A：

水题。

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

int a, b;

int main() {
    cin >> a >> b;
    cout << max(max(a + b, a - b), a * b) << endl;
    return 0;
}

B：

一开始还看错题了。

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

const int lim = 1e6;
int k, x;

int main() {
    cin >> k >> x;
    for (int i = x - k + 1; i <= x + k - 1; i++) {
        if (i < -lim || i > lim) continue;
        cout << i << " ";
    }
    puts("");
    return 0;
}

C：

所有字符串自身sort一遍后再sort一遍，对于重复的字符串，ans+=C(重复个数,2)。

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 1e5 + 10;
int n;
string s[maxn];
ll ans = 0;

int main() {
    scanf("%d", &n);
    rep1(i, 1, n) {
        cin >> s[i];
        sort(s[i].begin(), s[i].end());
    }
    sort(s + 1, s + 1 + n);
    int cnt = 1;
    rep1(i, 2, n) {
        if (s[i] == s[i - 1]) cnt++;
        else {
            ans += (ll)cnt * (cnt - 1) / 2;
            cnt = 1;
        }
    }
    ans += (ll)cnt * (cnt - 1) / 2;
    printf("%lld
", ans);
    return 0;
}

D：

正向思考非常麻烦，不妨倒着枚举还剩多少天。用一个优先队列维护可做工作的最大收益即可。

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 1e5 + 10;
// const int maxn = 5;
struct Job {
    int earn, wait;
    bool operator<(const Job &rhs)const {
        if (wait != rhs.wait) return wait < rhs.wait;
        else return earn > rhs.earn;
    }
} a[maxn];
int n, m, tot = 0, p = 0;
ll ans = 0;

int main() {
    scanf("%d%d", &n, &m);
    rep1(i, 1, n) {
        int earn, wait; scanf("%d%d", &wait, &earn);
        if (wait > m) continue;
        a[++tot].wait = wait; a[tot].earn = earn;
    }
    int p = 0;
    sort(a + 1, a + 1 + tot);
    priority_queue<int>q;
    while (!q.empty()) q.pop();
    for (int reDay = 1; reDay <= m && p <= tot; reDay++) {
        while (p < tot && a[p + 1].wait <= reDay) {
            p++; q.push(a[p].earn);
        }
        if (!q.empty()) ans += (ll)q.top();
        if (!q.empty()) q.pop();
    }
    printf("%lld
", ans);
    return 0;
}

E：

Bellmen-ford最短路。

F：

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

struct CombineSmall {
    int m;
    vector<vector<int>> F;
    CombineSmall(int n, int m): m(m), F(n) {
        for (int i = 1; i < n; i++) F[i].resize(i + 1);
    }
    int com(int n, int k) {
        return !k ? 1 : k > n ? 0 : k + k > n ? com(n, n - k) : F.at(n)[k] ? F[n][k] : F[n][k] = (com(n - 1, k) + com(n - 1, k - 1)) % m;
    }
};

int main() {
    int p; scanf("%d", &p);
    vector<int>b(p);
    CombineSmall cb(p, p);
    for (int i = 0; i < p; i++) {
        int ai; scanf("%d", &ai);
        if (!ai) continue;
        vector<int> pa(p); pa[0] = 1;
        for (int j = 1; j < p; j++) pa[j] = (ll)pa[j - 1] * i % p;
        b[0] = (b[0] + 1) % p;
        for (int j = 0; j < p; j++) {
            int cof = (ll)cb.com(p - 1, j) * pa[p - 1 - j] % p;
            if (~(p - 1 - j) & 1) cof = p - cof;
            b[j] = (b[j] + cof) % p;
        }
    }
    for (int i = 0; i < p; i++) printf("%d%c", b[i], i == p - 1 ? '
' : ' ');
    return 0;
}