原题链接：

A.Cirno’s Perfect Bitmasks Classroom

思路

代码

#include <bits/stdc++.h>
using namespace std;
int main()
{
    int T;
    cin >> T;
    while(T--)
    {
        int ans;
        int x;
        cin >> x;
        int low1;
        int low0;
        int cnt1;
        low1 = low0 = -1;
        cnt1 = 0;
        bool fir1 = false;
        bool fir0 = false;
        for(int i = 0; i <= 31; i++)
        {
            int t = (x>>i) & 1;
            if(!t && !fir0)
            {
                fir0 = true;
                low0 = i;
            }
            if(t)
            {
                cnt1 ++;
                if(!fir1)
                {
                    low1 = i;
                    fir1 = true;
                }
            }
        }
        if(cnt1 > 1)
        {
            ans = (1<<low1);
        }
        else
        {
            ans = (1 << low1) + (1 << low0);
        }
        printf("%d\n", ans);
    }
    return 0;
}
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B.Patchouli’s Magical Talisman

思路

代码

#include <bits/stdc++.h>
using namespace std;
int H[50];
void process()
{
    for(int i = 0; i <= 35; i++)
    {
        H[((long long)1 << i)%37] = i;
    }
}
int  main()
{
    process();
    int T;
    cin >> T;
    while(T--)
    {
        int ans;
        int num_even = 0;
        int minn = INT_MAX;
        int buf;
        int n;
        scanf("%d", &n);
        for(int i = 1; i <= n; i++)
        {
            scanf("%d", &buf);
            if(H[(buf & (-buf))%37] != 0)
            {
                num_even ++;
            }
            minn = min(minn, H[(buf & (-buf))%37]);
        }
        if(minn == 0)
            ans = num_even;
        else
            ans = num_even-1+minn;
        printf("%d\n", ans);

    }
    return 0;
}
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C.Manipulating History

思路

代码

#include <bits/stdc++.h>
using namespace std;
#define N 200010
char buf[N];
int cnt[300];
int main()
{
    int T;
    cin >> T;
    while(T--)
    {
        char ans;
        memset(cnt, 0, sizeof(cnt));
        int n;
        scanf("%d", &n);
        for(int i = 1; i <= 2*n+1; i++)
        {
            scanf("%s", buf+1);
            int len = strlen(buf+1);
            for(int j = 1; j <= len; j++)
            {
                int p = buf[j];
                cnt[p] = (cnt[p]+1) % 2;
            }
        }
        for(int i = 'a'; i <= 'z'; i++)
        {
            if(cnt[i]&1 == 1)
            {
                ans = i;
                break;
            }
        }
        printf("%c\n", ans);
    }
    return 0;
}
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D.The Enchanted Forest

思路

代码

#include <bits/stdc++.h>
using namespace std;
#define N 200010
int s[N];
int main()
{
    int T;
    cin >> T;
    while(T--)
    {
        long long ans = 0;
        int n, k;
        scanf("%d%d", &n, &k);
        for(int i = 1; i <= n; i++)
        {
            scanf("%d", s+i);
        }
        if(k >= n)
        {
            for(int i = 1; i <= n; i++)
            {
                ans += s[i];
            }
            ans += (long long)(k-1) * n;
            ans -= (long long)n * (n-1) / 2;
        }
        else
        {
            long long tmp = 0;
            int l = 1;
            int r = k;
            for(int i = 1; i <= r; i++) tmp += s[i];
            ans = tmp;
            while(r+1 <= n)
            {
                tmp-=s[l++];
                tmp+=s[++r];
                ans = max(tmp, ans);
            }
            ans += (long long)k*(k-1)/2;
        }
        printf("%lld\n", ans);
    }
    return 0;
}
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E.Railway System

思路

代码

#include <bits/stdc++.h>
using namespace std;
priority_queue<pair<int, int> > pq;
int n, m;
int edge[600];

void ask(int k, bool tag)
{
    printf("? ");
    for(int i = 1; i <= k-1; i++)
    {
        if(tag) putchar('0');
        else putchar('1');
    }
    if(tag) putchar('1');
    else putchar('0');
    for(int i = k+1; i <= m; i++)
    {
        if(tag) putchar('0');
        else putchar('1');
    }
    putchar('\n');
    fflush(stdout);
}

void que()
{
    printf("? ");
    for(int i = 1; i <= m; i++)
    {
        printf("%d", edge[i]);
    }
    putchar('\n');
    fflush(stdout);
}
int main()
{
    int ans = 0;
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= m; i++)
    {
        int buf = 0;
        ask(i, true);
        scanf("%d", &buf);
        pq.push(make_pair(buf, i));
    }
    for(int i = 1; i <= m; i++) edge[i] = 1;
    que();
    int res;
    int last;
    scanf("%d", &res);
    last = res;
    for(int i = 1; i <= m-1; i++)
    {
        pair<int, int>t;
        t = pq.top();
        pq.pop();
        edge[t.second] = 0;
        que();
        scanf("%d", &res);
        if(last - res < t.first);//并不需要干什么事情
        else
        {
            ans += t.first;
        }
        last = res;
    }
    ans += pq.top().first;
    printf("! ");
    printf("%d", ans);
    fflush(stdout);
    return 0;
}
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