BZOJ 2428: [HAOI2006]均分数据
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/* 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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