• C. Permutation Cycle


    For a permutation P[1... N] of integers from 1 to N, function f is defined as follows:

    Let g(i) be the minimum positive integer j such that f(i, j) = i. We can show such j always exists.

    For given N, A, B, find a permutation P of integers from 1 to N such that for 1 ≤ i ≤ Ng(i) equals either A or B.

    Input

    The only line contains three integers N, A, B (1 ≤ N ≤ 106, 1 ≤ A, B ≤ N).

    Output

    If no such permutation exists, output -1. Otherwise, output a permutation of integers from 1 to N.

    Examples
    input
    Copy
    9 2 5
    output
    6 5 8 3 4 1 9 2 7
    input
    Copy
    3 2 1
    output
    1 2 3 
    Note

    In the first example, g(1) = g(6) = g(7) = g(9) = 2 and g(2) = g(3) = g(4) = g(5) = g(8) = 5

    In the second example, g(1) = g(2) = g(3) = 1

    这题就是求 Ax+By=N 是否存在非负解,且 x,y解就是A,B的组数,每组将最前面的数丢到最后即可

    扩展欧几里得求不定方程

    #include <bits/stdc++.h>
    using namespace std;
    typedef long long ll;
    #define inf 2147483647
    const ll INF = 0x3f3f3f3f3f3f3f3fll;
    #define ri register int
    template <class T> inline T min(T a, T b, T c)
    {
        return min(min(a, b), c);
    }
    template <class T> inline T max(T a, T b, T c)
    {
        return max(max(a, b), c);
    }
    template <class T> inline T min(T a, T b, T c, T d)
    {
        return min(min(a, b), min(c, d));
    }
    template <class T> inline T max(T a, T b, T c, T d)
    {
        return max(max(a, b), max(c, d));
    }
    #define scanf1(x) scanf("%d", &x)
    #define scanf2(x, y) scanf("%d%d", &x, &y)
    #define scanf3(x, y, z) scanf("%d%d%d", &x, &y, &z)
    #define scanf4(x, y, z, X) scanf("%d%d%d%d", &x, &y, &z, &X)
    #define pi acos(-1)
    #define me(x, y) memset(x, y, sizeof(x));
    #define For(i, a, b) for (int i = a; i <= b; i++)
    #define FFor(i, a, b) for (int i = a; i >= b; i--)
    #define bug printf("***********
    ");
    #define mp make_pair
    #define pb push_back
    const int N = 1000005;
    // name*******************************
    ll n,a,b;
    ll x0,y0;
    
    // function******************************
    ll exgcd(ll a,ll b,ll &x,ll &y)
    {
        if(b==0)
        {
            x=1;
            y=0;
            return a;
        }
        ll g=exgcd(b,a%b,x,y);
        ll t=x;
        x=y;
        y=t-(a/b)*y;
        return g;
    }
    
    //***************************************
    int main()
    {
    //    ios::sync_with_stdio(0);
    //    cin.tie(0);
        // freopen("test.txt", "r", stdin);
        //  freopen("outout.txt","w",stdout);
        cin>>n>>a>>b;
        ll g=exgcd(a,b,x0,y0);
        ll k1=x0*n/g,k2=y0*n/g;
        ll t=1;
        ll a1=a,b1=b;
        a/=g;  //求通解时这里的a,b一定要除以最大公约数!!!
        b/=g;
        if(n%g)
        {
            cout<<-1;
            return 0;
        }
    
        if(k1<0)
        {
            t=(-k1)/b;
            if((-k1)%b)t++;
            if(k2-a*t<0)
            {
                cout<<-1;
                return 0;
            }
            k1+=b*t;
            k2-=a*t;
        }
        if(k2<0)
        {
            t=(-k2)/a;
            if((-k2)%a)t++;
            if(k1-b*t<0)
            {
                cout<<-1;
                return 0;
            }
            k2+=a*t;
            k1-=b*t;
        }
    
    
        queue<ll>q;
        For(i,1,n)
        {
            q.push(i);
        }
        For(i,1,k1)
        {
            ll x=q.front();
            q.pop();
            For(j,1,a1-1)
            {
                cout<<q.front()<<" ";
                q.pop();
            }
            cout<<x<<" ";
        }
        For(i,1,k2)
        {
            ll x=q.front();
            q.pop();
            For(j,1,b1-1)
            {
                cout<<q.front()<<" ";
                q.pop();
            }
            cout<<x<<" ";
        }
    
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/planche/p/8733169.html
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