Codeforces Round #568 (div. 2)

题目链接：https://codeforces.com/contest/1185

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A：

水。

/* 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)
#define mid (curl+curr>>1)
/* namespace */
using namespace std;
/* header end */

int a[4], d;

int main() {
    cin >> a[1] >> a[2] >> a[3] >> d;
    sot(a, 3);
    cout << (d - (a[2] - a[1]) >= 0 ? d - (a[2] - a[1]) : 0) + (d - (a[3] - a[2]) >= 0 ? d - (a[3] - a[2]) : 0) << endl;
    return 0;
}

B：

扫一遍完事。

/* 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)
#define mid (curl+curr>>1)
/* namespace */
using namespace std;
/* header end */

int n;

int main() {
    cin >> n;
    while (n--) {
        string a, b; cin >> a >> b;
        int i = 0, j = 0, aLen = a.size(), bLen = b.size();
        while (i < aLen || j < bLen) {
            if (a[i] == b[j]) i++, j++;
            else if (j && b[j] == b[j - 1]) j++;
            else break;
        }
        if (i == aLen && j == bLen) puts("YES");
        else puts("NO");
    }
    return 0;
}

C1：

贪心。每读一个就sort一次，然后扫一遍维护ans[i]和sum。

/* 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)
#define mid (curl+curr>>1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 2e5 + 10;
int n, m, a[maxn] = {0}, b[maxn] = {0};

int main() {
    scanf("%d%d", &n, &m);
    rep0(i, 0, n) {
        cin >> a[i];
        sort(a, a + i);
        ll sum = 0;
        rep1(j, 0, i)
        if (sum + a[i] + a[j] > m) {
            b[i] = i - j;
            break;
        } else sum += a[j];
    }
    rep0(i, 0, n) printf("%d ", b[i]);
    puts("");
    return 0;
}

C2：

贪心+枚举时间戳。

/* 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)
#define mid (curl+curr>>1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 2e5 + 10;
int n, m, a[maxn], b[maxn], time[110];

int main() {
    scanf("%d%d", &n, &m);
    rep0(i, 0, n) scanf("%d", &a[i]);
    rep0(i, 0, 110) time[i] = 0;
    int s = 0, sum = 0, ss = 0, delta1 = 0, delta2 = 0;
    rep0(i, 0, n) {
        s += a[i];
        if (s > m) {
            delta1 = s - m;
            ss = 0;
            for (int j = 100; j >= 1; j--) // enum each time slot
                if (time[j]) {
                    sum += j * time[j];
                    ss += time[j];
                    if (sum > delta1) {
                        delta2 = sum - delta1;
                        ss -= delta2 / j;
                        break;
                    }
                }
            b[i] = ss;
            sum = 0;
        } else b[i] = 0;
        time[a[i]]++;
    }
    rep0(i, 0, n) printf("%d ", b[i]);
    puts("");
    return 0;
}

D：

暴力。n==2时必定成立。sort一遍，枚举三种状态即可：删了最小的、删了最大的、删了中间某个。然后分别检查是否成立即可。

/* 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)
#define mid (curl+curr>>1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 2e5 + 10;
struct Node {
    Node() {}
    int val, posi;
    bool operator<(const Node &rhs)const {
        return val < rhs.val;
    }
} a[maxn];
int n;
vector<Node>b;

int main() {
    scanf("%d", &n);
    rep1(i, 1, n) {
        scanf("%d", &a[i].val);
        a[i].posi = i;
    }
    if (n == 2) return puts("1"), 0;
    sot(a, n);
    int s = a[n].val - a[1].val, pos = 1, d = s / (n - 2), cnt = 0;
    rep1(i, 1, n)
    if (a[i].val != a[1].val + d * (i - cnt - 1)) {
        pos = a[i].posi;
        cnt++;
    }
    if (cnt == 1) return printf("%d\n", pos), 0;
    s = a[n - 1].val - a[1].val; d = s / (n - 2);
    int flag = 0;
    rep1(i, 1, n - 1)
    if (a[i].val != a[1].val + d * (i - 1))
        flag = 1;
    if (!flag) return printf("%d\n", a[n].posi), 0;
    flag = 0; s = a[n].val - a[2].val; d = s / (n - 2);
    rep1(i, 2, n)
    if (a[i].val != a[2].val + d * (i - 2))
        flag = 1;
    if (!flag) return printf("%d\n", a[1].posi), 0;
    puts("-1");
    return 0;
}

E：

大模拟，不是很好写，我实在是写不动这种东西……

F：

位运算暴力题。

G1 && G2：

这个就真的不会了.