Codeforces Round #578 (Div. 2)

比较简单暴力的一场。

题目链接：http://codeforces.com/contest/1200

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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 */

const int maxn = 1e5 + 10;
int n, a[20];
char s[maxn];

int main() {
    scanf("%d", &n);
    scanf("%s", s + 1);
    for (int i = 1; i <= n; i++) {
        if (s[i] == 'L') {
            for (int i = 0; i < 10; i++)
                if (!a[i]) {
                    a[i] = 1; break;
                }
        } else if (s[i] == 'R') {
            for (int i = 9; i >= 0; i--)
                if (!a[i]) {
                    a[i] = 1; break;
                }
        } else a[s[i] - '0'] = 0;
    }
    for (int i = 0; i < 10; i++) printf("%d", a[i]);
    puts("");
    return 0;
}

B：

贪心，注意h[i]<h[i+1]时也可以攒石头。

/* 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 main() {
    int t; scanf("%d", &t);
    while (t--) {
        ll n, m, k; scanf("%lld%lld%lld", &n, &m, &k);
        ll h[n + 1], solved = 1;
        for (int i = 1; i <= n; i++) scanf("%lld", &h[i]);
        for (int i = 1; i < n; i++) {
            if (h[i] >= h[i + 1]) {
                m += h[i] - h[i + 1];
                h[i] = h[i + 1];
                m += min(h[i], k);
            } else {
                if (h[i + 1] - h[i] - m > k) {
                    solved = 0; break;
                } else {
                    if (h[i + 1] - h[i] <= k)
                        m += min(h[i], h[i] - (h[i + 1] - k));
                    else
                        m -= h[i + 1] - h[i] - k;
                }
            }
        }
        if (solved) puts("YES"); else puts("NO");
    }
    return 0;
}

C：

求个gcd就看出来了。

/* 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 */

ll n, m;
int q;

int main() {
    scanf("%lld%lld%d", &n, &m, &q);
    ll gcd = __gcd(n, m);
    ll awall = n / gcd, bwall = m / gcd;
    while (q--) {
        ll x, y, p, q; scanf("%lld%lld%lld%lld", &x, &y, &p, &q);
        ll tmpa, tmpb;
        if (x == 1)
            tmpa = y % awall ? y / awall : y / awall - 1;
        else
            tmpa = y % bwall ? y / bwall : y / bwall - 1;
        if (p == 1)
            tmpb = q % awall ? q / awall : q / awall - 1;
        else
            tmpb = q % bwall ? q / bwall : q / bwall - 1;
        if (tmpa == tmpb) puts("YES"); else puts("NO");
    }
    return 0;
}

D：

O(n²)暴力可以过。

E：

kmp。

/* 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 ans;

int kmp(string s) {
    vector<int> tmp(s.size());
    for (int i = 1; i < s.size(); i++) {
        int k = tmp[i - 1];
        while (s[k] != s[i]) {
            if (!k) {
                k = -1; break;
            }
            k = tmp[k - 1];
        }
        tmp[i] = k + 1;
    }
    return tmp.back();
}

int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        if (!i) {
            cin >> ans;
            continue;
        }
        string s; cin >> s; string t = s + '#';
        int a = min((int)ans.size(), (int)s.size());
        t.insert(t.end(), ans.end() - a, ans.end());
        int x = kmp(t);
        while (x--) ans.pop_back();
        ans.insert(ans.end(), s.begin(), s.end());
    }
    cout << ans << endl;
    return 0;
}