Rearrange20100224

/*给定函数fun的功能是计算形参x所指的数组中N个数的平均值（规定所有数均为正数），将所指数组中大于平均数的值的数据移至数组的前部，小于平均数的数据移至x所致数组的后部。平均值作为函数的返回值。例如：有10个正数：46 30 32 40 6 17 45 15 48 26，平均值为：30.500000.移动后的输出为：46 32 40 45 48 30 6 17 15 26 */#include <stdlib.h>#include <stdio.h>//printf#include <malloc.h>#include <math.h>//#define N 10#define TypeX double//unused but possible generalizedouble Sum(const int N, double *x){double s = 0;for (int i = 0; i < N; i++){s += x[i];}return s;}double Avg(const int N, double *x){return (Sum(N, x) / N);}inline double swap(double *a, double *b){register double c;c = *a;*a = *b;*b = c;}//length of array must >= 1double Rearrange2010_02_24(const int N, double *x){if (NULL == x)return NAN;if (0 == N)return NAN;if (1 == N)return *x;const double avg = Avg(N, x);double *p = x + N - 1;//points to last element of arraydo{if (*x >= avg){x++;continue;}swap(x, p);//bad element swap to endp--;// points to last un-tested element} while (x < p);return avg;}int main(){const int ARRAY_LEN = 10;double data[] = { 46, 30, 32, 40, 6, 17, 45, 15, 48, 26 };printf("test data: len=%d/n", ARRAY_LEN);for (int i = 0; i < ARRAY_LEN; i++){printf("%.f,", data[i]);}printf("/nanalyzing.../n");double avg = Rearrange2010_02_24(ARRAY_LEN, data);printf("avg=%f/n", avg);printf("after:/n");for (int i = 0; i < ARRAY_LEN; i++){printf("%.f,", data[i]);}printf("/n");exit(EXIT_SUCCESS);}

 

output

test data: len=10
46,30,32,40,6,17,45,15,48,26,
analyzing...
avg=30.500000
after:
46,48,32,40,45,17,15,6,26,30,
Press any key to continue...

 

for

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