47 lines
1.4 KiB
C++
47 lines
1.4 KiB
C++
#include<stdio.h>
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#include<math.h>
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#include <string.h>
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#define INF 1<<29
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int map[9][9],sum[9][9];
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int d[15][9][9][9][9];
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inline int Min(int a,int b){return a>b?b:a;}
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int s(int x1,int y1,int x2,int y2){
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int temp=sum[x2][y2]-sum[x1-1][y2]-sum[x2][y1-1]+sum[x1-1][y1-1]; return temp*temp;
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}
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int dp(int k,int x1,int y1,int x2,int y2){
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if(d[k][x1][y1][x2][y2]!=-1)return d[k][x1][y1][x2][y2];
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if(k==1)return s(x1,y1,x2,y2);
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int ans=INF,i;
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for(i=x1;i<x2;i++)
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{
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ans=Min(dp(k-1,x1,y1,i,y2)+s(i+1,y1,x2,y2),ans);
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ans=Min(dp(k-1,i+1,y1,x2,y2)+s(x1,y1,i,y2),ans);
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}
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for(i=y1;i<y2;i++)
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{
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ans=Min(dp(k-1,x1,y1,x2,i)+s(x1,i+1,x2,y2),ans);
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ans=Min(dp(k-1,x1,i+1,x2,y2)+s(x1,y1,x2,i),ans);
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}
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return d[k][x1][y1][x2][y2]=ans;
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}
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int main()
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{
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int n,i,j,k;
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while(~scanf("%d",&n)){
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memset(map,0,sizeof(map));
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for(i=1;i<=8;i++)
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for(j=1;j<=8;j++)
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scanf("%d",&map[i][j]);
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memset(sum,0,sizeof(sum));
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for(i=1;i<=8;i++)
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for(j=1;j<=8;j++)
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sum[i][j]=sum[i-1][j]+sum[i][j-1]-sum[i-1][j-1]+map[i][j];
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memset(d,-1,sizeof(d));
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int ans=dp(n,1,1,8,8);
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double aver=(double)sum[8][8]/(double)n;
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double last=sqrt((double)ans/(double)n-aver*aver);
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printf("%.3lf\n",last);
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}
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return 0;
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}
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