Codeforces_814

A.b序列从大到小填a序列中的0，在判断。

#include<bits/stdc++.h>
using namespace std;

int n,m,a[105],b[105];

int main()
{
    ios::sync_with_stdio(0);
    cin >> n >> m;
    for(int i = 1;i <= n;i++)   cin >> a[i];
    for(int i = 1;i <= m;i++)   cin >> b[i];
    sort(b+1,b+1+m);
    reverse(b+1,b+1+m);
    int now = 0;
    for(int i = 1;i <= n;i++)
    {
        if(a[i] == 0)   a[i] = b[++now];
    }
    for(int i = 2;i <= n;i++)
    {
        if(a[i-1] > a[i])
        {
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
    return 0;
}

---

B.分一个位置不同和两个位置不同两种情况。一个位置不同的直接改成没出现的数字。两个位置不同的把两种情况都试一下。

#include<bits/stdc++.h>
using namespace std;

int n,a[1005],b[1005],c[1005],ok[1005] = {0},x[3];

int main()
{
    ios::sync_with_stdio(0);
    cin >> n;
    for(int i = 1;i <= n;i++)   cin >> a[i];
    for(int i = 1;i <= n;i++)   cin >> b[i];
    int cnt = 0;
    for(int i = 1;i <= n;i++)
    {
        if(a[i] == b[i])    ok[a[i]] = 1;
        else    x[++cnt] = i;
    }
    if(cnt == 1)
    {
        for(int i = 1;i <= n;i++)
        {
            if(!ok[i])  a[x[1]] = i;
        }
    }
    else
    {
        for(int i = 1;i <= n;i++)   c[i] = a[i];
        for(int i = 1;i <= n;i++)
        {
            if(!ok[i])
            {
                a[x[1]] = i;
                ok[i] = 1;
                break;
            }
        }
        for(int i = 1;i <= n;i++)
        {
            if(!ok[i])  a[x[2]] = i;
        }
        int cnt1 = 0,cnt2 = 0;
        for(int i = 1;i <= n;i++)
        {
            if(a[i] != b[i])    cnt1++;
            if(a[i] != c[i])    cnt2++;
        }
        if(cnt1 != 1 || cnt2 != 1)  swap(a[x[1]],a[x[2]]);
    }
    for(int i = 1;i <= n;i++)   cout << a[i] << " ";
    return 0;
}

---

C.打表每个字母增加每个数值的ans。

#include<bits/stdc++.h>
using namespace std;

int n,q,ans[128][1505] = {0},cnt[1505];
string s;

int main()
{
    ios::sync_with_stdio(0);
    cin >> n >> s >> q;
    s = ' '+s;
    for(char c = 'a';c <= 'z';c++)
    {
        memset(cnt,0,sizeof(cnt));
        for(int i = 1;i <= n;i++)
        {
            cnt[i] = cnt[i-1];
            if(s[i] != c)   cnt[i]++;
        }
        for(int i = 0;i <= n;i++)
        {
            for(int j = i+1;j <= n;j++)
            {
                ans[c][cnt[j]-cnt[i]] = max(ans[c][cnt[j]-cnt[i]],j-i);
            }
        }
        for(int i = 1;i <= n;i++)   ans[c][i] = max(ans[c][i-1],ans[c][i]);
    }
    while(q--)
    {
        int x;
        cin >> x >> s;
        cout << ans[s[0]][x] << endl;
    }
    return 0;
}

---

D.判断每个环在第几层，0层和偶数层的加，奇数层的减。

#include<bits/stdc++.h>
#define PI acos(-1)
using namespace std;

int n,x[1005],y[1005],r[1005],cnt[1005] = {0};

int main()
{
    ios::sync_with_stdio(0);
    cin >> n;
    for(int i = 1;i <= n;i++)   cin >> x[i] >> y[i] >> r[i];
    for(int i = 1;i <= n;i++)
    {
        for(int j = 1;j <= n;j++)
        {
            if(i == j)  continue;
            if(sqrt(1.0*(x[i]-x[j])*(x[i]-x[j])+1.0*(y[i]-y[j])*(y[i]-y[j])) <= r[j]-r[i])  cnt[i]++;
        }
    }
    double ans = 0;
    for(int i = 1;i <= n;i++)
    {
        if(cnt[i] == 0 || cnt[i]%2) ans += PI*r[i]*r[i];
        else    ans -= PI*r[i]*r[i];
    }
    cout << fixed << setprecision(10) << ans << endl;
    return 0;
}