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  • BZOJ 2428: [HAOI2006]均分数据

    二次联通门 : BZOJ 2428: [HAOI2006]均分数据

    /*
        BZOJ 2428: [HAOI2006]均分数据
        
        模拟退火初体验 
        完全随机化算法
        估计对我这种非酋来说的话估计是用处不大了吧23333 
    */
    #include <cstdio>
    #include <iostream>
    #include <cstdlib>
    #include <algorithm>
    #include <cmath>
    #include <ctime>
    #include <cstring>
    #define rg register
    inline void read (int &n)
    {
        rg char c = getchar ();
        for (n = 0; !isdigit (c); c = getchar ());
        for (; isdigit (c); n = n * 10 + c - '0', c = getchar ());
    }
    #define Max 1000
    #define INF 1e8
    int N, M, p[Max]; 
    using std :: swap;
    typedef double flo; flo a[Max], mn, s[Max], avg;
    inline flo Pow (flo x) { return x * x; }
    void BackFire ()
    {
        memset (s, 0, sizeof s); flo r = 0, T; rg int i;
        for (i = 1; i <= N; ++ i) p[i] = rand () % M + 1, s[p[i]] += a[i];
        flo k; int x, y;
        for (i = 1; i <= M; ++ i) r += (s[i] - avg) * (s[i] - avg);
        for (T = 10000; T > 0.1; T *= 0.9)
        {
            k = r; x = rand () % N + 1;
            if (T > 500) y = std :: min_element (s + 1, s + 1 + M) - s;
            else y = rand () % M + 1;
            if (p[x] == y) continue;
            r -= Pow(s[p[x]] - avg), r += Pow(s[p[x]] - a[x] - avg);
            r -= Pow(s[y] - avg), r += Pow(s[y] + a[x] - avg);
            if (rand () % 100000 + 1 > T && r > k) r = k;
            else s[p[x]] -= a[x], s[y] += a[x], p[x] = y;
        }
        if (r < mn) mn = r;
    }
    int main (int argc, char *argv[])
    {
        read (N), read (M); rg int i;
        for (i = 1; i <= N; ++ i) scanf ("%lf", &a[i]), avg += i[a], swap (a[i], a[rand () % i + 1]);
        avg /= (flo) M, mn = INF;
        for (i = 1; i <= 5000; ++ i) BackFire ();
        printf ("%.2lf", sqrt (mn / (flo) M)); return 0;
    }
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  • 原文地址:https://www.cnblogs.com/ZlycerQan/p/7672850.html
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