poj1191

#include<iostream>#include<cstring>#include<cmath>using namespace std;int value[9][9];int dp[16][9][9][9][9];int cal_min(int x, int y){if (x > y){return y;}else{return x;}}int sum(int x1,int y1,int x2,int y2){int x, y,sum=0;x = x1;y = y1;while (x <= x2){while (y <= y2){sum += value[x][y];y++;}x++;y = y1;}return sum;}int cut(int n, int x1, int y1, int x2, int y2){int s1, s2,x,y,tmp1,tmp2,min=10000000;//min太小会WAif (dp[n][x1][y1][x2][y2] != -1){return dp[n][x1][y1][x2][y2];}if (n == 1){s1 = sum(x1, y1, x2, y2);return dp[1][x1][y1][x2][y2] = s1*s1;}for (x = x1; x < x2; x++)//横切{s1 = sum(x1, y1, x, y2);s2 = sum(x + 1, y1, x2, y2);tmp1 = cal_min(cut(n-1,x+1,y1,x2,y2)+s1*s1, cut(n-1,x1,y1,x,y2)+s2*s2);if (tmp1 < min){min = tmp1;}}for (y = y1; y < y2; y++){s1 = sum(x1, y1, x2, y);s2 = sum(x1, y + 1, x2, y2);tmp2 = cal_min(cut(n - 1, x1, y + 1, x2, y2)+s1*s1, cut(n - 1, x1, y1, x2, y)+s2*s2);if (tmp2 < min){min = tmp2;}}return dp[n][x1][y1][x2][y2] = min;}int main(){int n,i,j,total=0,res;double avar, ans;scanf("%d", &n);memset(dp, -1, sizeof(dp));for (i = 1; i < 9; i++){for (j = 1; j < 9; j++){scanf("%d", &value[i][j]);total += value[i][j];}}avar = 1.0*total / n;res = cut(n, 1, 1, 8, 8);ans = sqrt(1.0*res / n - avar*avar);printf("%.3lf\n", ans);}