bzoj 2428 均分数据 模拟退火

模拟退火

按照自己的思路打了，结果WA，发现退火最关键的就是初温，降温，和修改次数，

这个题还在外层带了一个循环，骚气

#include<cstdio>#include<iostream>#include<cstring>#include<algorithm>#include<cmath>#define inf 0x3f3f3f3f3f3f3f3fllusing namespace std;double av,ans,minn=inf,sum[30];int n,m,a[30],be[30];double Rand(){return (rand()%1000)/1000.0;}void work(){memset(sum,0,sizeof sum);ans=0;for(int i=1;i<=n;i++)be[i]=rand()%m+1,sum[be[i]]+=a[i];for(int i=1;i<=m;i++)ans+=(sum[i]-av)*(sum[i]-av);double t=10000;while(t>0.1){int x=rand()%n+1,y=be[x],z;if(t>500)z=min_element(sum+1,sum+m+1)-sum;else z=rand()%m+1;double nxt=ans;nxt-=(sum[y]-av)*(sum[y]-av);nxt-=(sum[z]-av)*(sum[z]-av);sum[y]-=a[x]; sum[z]+=a[x];nxt+=(sum[y]-av)*(sum[y]-av);nxt+=(sum[z]-av)*(sum[z]-av);double dE=ans-nxt;if(dE>0||exp(dE/t)>Rand())ans=nxt,be[x]=z;elsesum[y]+=a[x],sum[z]-=a[x];t*=0.9;}if(ans<minn) minn=ans;}int main(){srand(20001101);scanf("%d%d",&n,&m);for(int i=1;i<=n;i++){scanf("%d",&a[i]);av+=a[i];}av/=m;for(int i=1;i<=10000;i++)work();printf("%0.2lf\n",sqrt(minn/m));return 0;}