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  • CF959D Mahmoud and Ehab and another array construction task 数学

    Mahmoud has an array a consisting of n integers. He asked Ehab to find another array b of the same length such that:

    • b is lexicographically greater than or equal to a.
    • bi ≥ 2.
    • b is pairwise coprime: for every 1 ≤ i < j ≤ n, bi and bj are coprime, i. e. GCD(bi, bj) = 1, where GCD(w, z) is the greatest common divisor of w and z.

    Ehab wants to choose a special array so he wants the lexicographically minimal array between all the variants. Can you find it?

    An array x is lexicographically greater than an array y if there exists an index i such than xi > yi and xj = yj for all 1 ≤ j < i. An array x is equal to an array y if xi = yi for all 1 ≤ i ≤ n.

    Input

    The first line contains an integer n (1 ≤ n ≤ 105), the number of elements in a and b.

    The second line contains n integers a1, a2, ..., an (2 ≤ ai ≤ 105), the elements of a.

    Output

    Output n space-separated integers, the i-th of them representing bi.

    Examples
    Input
    Copy
    5
    2 3 5 4 13
    Output
    Copy
    2 3 5 7 11 
    Input
    Copy
    3
    10 3 7
    Output
    Copy
    10 3 7 
    Note

    Note that in the second sample, the array is already pairwise coprime so we printed it.

    求一个互素的序列且字典序比 A 序列大的最小序列;

    显然,当某一位置的 b[ i ]> a[ i ] 时,我们只需要安排剩下的数使得 b 数列互素即可;

    那么这个我们可以用 fg 来标记一下;

    如何保证我们的序列互素呢?考虑质因子,

    我们用 use 来看最小质因子是否有使用,如果已经使用,那么显然不能选用;

    #include<bits/stdc++.h>
    using namespace std;
    
    #define maxn 200005
    
    
    
    
    int prime[2000004],pre[2000004];
    int n;
    int a[maxn];
    int b[maxn];
    bool fg,vis[2000004],use[2000005];
    
    bool judge(int x)
    {
        // 检验 x 是否有已经用过的质因子
        int num[60],cnt=0;
        while(vis[x]){
            num[++cnt]=pre[x];x/=pre[x];
        }
        num[++cnt]=x;
        for(int i=1;i<=cnt;i++){
            if(use[num[i]])return false;
        }
        return true;
    }
    
    
    int main()
    {
        ios::sync_with_stdio(0);
        cin>>n;
        for(int i=1;i<=n;i++)cin>>a[i];
        int cnt=0;
        for(int i=2;i<=2000000;i++){
            if(!vis[i]){
                prime[++cnt]=i;
            }
            for(int j=1;j<=cnt;j++){
                int tmp=i*prime[j];
                if(tmp>2000000)break;
                vis[tmp]=1;
                pre[tmp]=prime[j];// 最小质因子
                if(i%prime[j]==0)break;
            }
        }
        int j=1;
        for(int i=1;i<=n;i++){
            if(fg){
                while(use[prime[j]])j++;
                b[i]=prime[j];
                use[prime[j]]=1;
            }
            else{
                int tmp=a[i];
                while(!judge(tmp))tmp++;
                if(tmp>a[i])fg=1;
                b[i]=tmp;
                while(vis[tmp]){
                    use[pre[tmp]]=1;tmp/=pre[tmp];
                }
                use[tmp]=1;
            }
        }
        for(int i=1;i<=n;i++)cout<<b[i]<<' ';
        cout<<endl;
    }
    
    EPFL - Fighting
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  • 原文地址:https://www.cnblogs.com/zxyqzy/p/10016852.html
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