题意：有8个数字全排列后带入公式计算，选出最小值。
题解：水题。
#include <stdio.h>
#include <math.h>
#include <algorithm>
using namespace std;
int flag[8][2] = {{-1, -1}, {-1, 0}, {1, 0}, {1, 1}, {0, -1}, {0, 1}, {-1, 1}, {1, -1}};
double arr[8];
int main() {
while (1) {
double sum = 0;
for (int i = 0; i < 8; i++) {
scanf("%lf", &arr[i]);
sum += arr[i];
}
if (fabs(sum - 0) < 1e-9)
break;
sort(arr, arr + 8);
double minn = 1 << 30;
do {
double temp1 = 0, temp2 = 0;
for (int i = 0; i < 8; i++) {
temp1 = temp1 + arr[i] * flag[i][0];
temp2 = temp2 + arr[i] * flag[i][1];
}
double temp = sqrt(temp1 * temp1 + temp2 * temp2);
minn = min(minn, temp);
} while (next_permutation(arr, arr + 8));
printf("%.3lf\n", minn);
}
return 0;
}
