/* * ===================================================================================== * * Filename: arrydiff.cpp * * Description: test * * Version: 1.0 * Created: 2012年09月11日 22时34分30秒 * Revision: none * Compiler: gcc * * Author: (http://blog.csdn.net/njzhiyuan) * Organization: * * ===================================================================================== */#include <iostream>extern "C" {#include <stdlib.h>#include <math.h>#include <time.h>}#include <string>using namespace std;/***sum_a 第一个数组的和*a 第一个数组中一个元素*sum_b 第二个数组的和*b 第二个数组中一个元素×函数返回假如交换a、b元素后，两数组元素之和的差，原始试子应为(sum_a - a + b) - (sum_b - b + a)*/template<typename T>inline T get_swap_diff(const T &sum_a, const T &a,const T &sum_b, const T &b){ return abs(sum_a - sum_b - 2 * a + 2 * b);}//此处在std里已有，这里属重复定义，故注释/*template<typename T>void swap(T &a, T &b){ T temp = a; a = b; b = temp;}*///求数组元素之和template<typename T, size_t element_nums>T array_sum(const T(&array)[element_nums]){ T sum = 0; for(size_t i = 0; i < element_nums; ++i) sum += *(array + i); return sum;}/***实现两个数组间元素的交换，使两数组元素之和的差最小，思想如下：*如果两数组元素之和的差已经最小，那么任意交换两数组的元素，都不能使差再减小，故这可以作为最外层循环的退出条件。*依次选取第一个数组的元素a，再从第二个数组中选出一元素b，使得a、b交换能使得两数组元素之和的差减小得最多。*交换a、b，重新计算两数组的两数组元素之和及它们的差。重复上述步骤，如果不能再使差减小了，就退出外层循环。*/template<typename T, size_t element_nums>void min_diff(T(&arr_a)[element_nums], T(&arr_b)[element_nums]){ bool flag; do{ flag = false; T sum_a = array_sum(arr_a); T sum_b = array_sum(arr_b); if(sum_a == sum_b) break; T diff = abs(sum_a - sum_b); for(size_t index_a = 0; index_a < element_nums; ++index_a){ size_t temp_index; bool chang_flag = false; for(size_t index_b = 0; index_b < element_nums; ++index_b){ if(diff > get_swap_diff(sum_a, *(arr_a + index_a), sum_b, *(arr_b + index_b))){ diff = get_swap_diff(sum_a, *(arr_a + index_a), sum_b, *(arr_b + index_b)); temp_index = index_b; chang_flag = true; } } if(chang_flag){ swap(*(arr_a + index_a),*(arr_b + temp_index)); //已调用swap交换了元素，两数组的两数组元素之和时须注意。 sum_a = sum_a + *(arr_a + index_a) - *(arr_b + temp_index); sum_b = sum_b + *(arr_b + temp_index) - *(arr_a + index_a); flag = true; } } }while(flag);}//显示数组元素template<typename T, size_t element_nums>void array_display(const T (&array)[element_nums]){ for(size_t i=0; i < element_nums; ++i) cout << *(array + i) << '\t'; cout << endl;}//给数组元素赋随机值template<typename T, size_t element_nums>void create_value(T (&array)[element_nums],int seed = 100){ size_t i = 0; srand((unsigned) time(NULL) + seed); while(i < element_nums){ *(array + i++) = static_cast<T>(rand() % 1000); }}// 下面的几个函数参数中，数组名作为是指针传递参数，实现的功能与以上同名函数相同template<typename T>T array_sum(const T *array, size_t element_nums){ T sum = 0; for(size_t i = 0; i < element_nums; ++i) sum += *(array + i); return sum;}template<typename T>void min_diff(T *arr_a,T *arr_b,size_t element_nums){ bool flag; do{ flag = false; T sum_a = array_sum(arr_a,element_nums); T sum_b = array_sum(arr_b,element_nums); if(sum_a == sum_b) break; T diff = abs(sum_a - sum_b); for(size_t index_a = 0; index_a < element_nums; ++index_a){ size_t temp_index; bool chang_flag = false; for(size_t index_b = 0; index_b < element_nums; ++index_b){ if(diff > get_swap_diff(sum_a, *(arr_a + index_a), sum_b, *(arr_b + index_b))){ diff = get_swap_diff(sum_a, *(arr_a + index_a), sum_b, *(arr_b + index_b)); temp_index = index_b; chang_flag = true; } } if(chang_flag){ swap(*(arr_a + index_a),*(arr_b + temp_index)); sum_a = sum_a + *(arr_a + index_a) - *(arr_b + temp_index); sum_b = sum_b + *(arr_b + temp_index) - *(arr_a + index_a); flag = true; } } }while(flag);}template<typename T>void array_display(const T *array,size_t element_nums){ for(size_t i=0; i < element_nums; ++i) cout << *(array + i) << '\t'; cout << endl;}template<typename T >void create_value(T *array,size_t element_nums,int seed = 100){ size_t i = 0; srand((unsigned) time(NULL) + seed); while(i < element_nums){ *(array + i++) = static_cast<T>(rand() % 1000); }}//指针形式参数系列函数的测试void pt_test(){ while(true){ size_t array_size; string size_temp; //避免直接cin>>array_size，因为输入非数值字符时，会导致意想不到的错误 cout << "Please input the size of array: "; cin>>size_temp; if((array_size = atol(size_temp.c_str())) < 1) array_size = 10; long *array_a; long *array_b; if((array_a = new long[array_size]) == NULL){ cout << "Apply space for the first array failed!"<<endl; break; } if((array_b = new long[array_size]) == NULL){ cout << "Apply space for the second array failed!"<<endl; delete[] array_a; break; } create_value(array_a,array_size); create_value(array_b,array_size,rand()); cout << "before the change:\n"; array_display(array_a,array_size); array_display(array_b,array_size); cout << "array_a sum " << array_sum(array_a,array_size) << endl; cout << "array_b sum " << array_sum(array_b,array_size) << endl; min_diff(array_a,array_b,array_size); cout << "after the change:\n"; array_display(array_a,array_size); array_display(array_b,array_size); cout << "array_a sum " << array_sum(array_a,array_size) << endl; cout << "array_b sum " << array_sum(array_b,array_size) << endl; delete[] array_a; delete[] array_b; cout << "Do you want to continue with this program? Y/N : "; char response; cin>>response; if(response != 'Y' && response != 'y') break; }}//引用形式参数系列函数的测试void ref_test(){ const size_t size =10; int array_a[size]; int array_b[size]; create_value(array_a); create_value(array_b,rand()); cout << "before the change:\n"; array_display(array_a); array_display(array_b); cout << "array_a sum " << array_sum(array_a) << endl; cout << "array_b sum " << array_sum(array_b) << endl; min_diff(array_a,array_b); cout << "after the change:\n"; array_display(array_a); array_display(array_b); cout << "array_a sum " << array_sum(array_a) << endl; cout << "array_b sum " << array_sum(array_b) << endl;}int main(int argc, char *argv[]){ ref_test(); pt_test(); return 0;}
