交换两个数组的元素使之总和的差值最小

Posted 2022-06-09 shixin_0125

题目描述：

          有两个数组a,b，大小都为n,数组元素的值任意整型数，无序；
          要求：通过交换a,b中的元素，使数组a元素的和与数组b元素的和之间的差最小。 

#include "stdafx.h"

#include <math.h>
#include <time.h>
#include <stdlib.h>

void print_arr(int a[], int b[], int n)

  printf("a: ");
  for (int i=0;i<n;i++)
  
    printf("%d ", a[i]);
  
  printf("\\n");
  printf("b: ");
  for (int i=0;i<n;i++)
  
    printf("%d ", b[i]);
  
  printf("\\n");
  printf("\\n");


bool swap_min(int a[], int b[], int n)

  printf("before swap:\\n");
  print_arr(a, b, n);

  // 初始化差值
  int sum_a=0;
  int sum_b=0;
  for (int k=0;k<n;k++)
  
    sum_a += a[k];
    sum_b += b[k];
  

  int delta_init = abs(sum_a - sum_b);

  for (int i=0;i<n;i++)
  
    /*if (delta_init == 0) // 优化处理
    
      break;
    */

    int sum_a=0;
    int sum_b=0;
    for (int k=0;k<n;k++)
    
      sum_a += a[k];
      sum_b += b[k];
    

    // 假设交换，差值是否更小
    bool bswp = false;
    int jpos = 0;
    for (int j=0;j<n;j++)
    
      int sum_atemp = sum_a-a[i]+b[j];
      int sum_btemp = sum_b-b[j]+a[i];
      int delta_temp = abs(sum_atemp-sum_btemp);
      if (delta_temp < delta_init)
      
        delta_init = delta_temp;
        jpos = j;
        bswp =true;
      
    

    // 假设成功，执行交换元素
    if (bswp)
    
      int tmp = a[i];
      a[i] = b[jpos];
      b[jpos] = tmp;
    
  

  printf("after swap:\\n");
  print_arr(a,b,n);

  return true;




int _tmain(int argc, _TCHAR* argv[])

  int a[5] = 0, 0, 0, 0, 9;//1,2,3,4,5
  int b[5] = 1, 2, 5, 4, 3;//6,7,8,9,100

  int c[] = 1,2,3,4,5;
  int d[] = 6,7,8,9,100;

  int e[]=1,2,3,4,5;
  int f[]=10,20,30,40,50;
  
  swap_min(a, b, 5);
  swap_min(c, d, 5);
  swap_min(e, f, 5);

  errno_t err;  
  unsigned int number;  
  err = rand_s(&number);  

  int m[100];
  int n[100];
  srand( (unsigned)time(NULL)); //生成种子
  for (int i=0;i<100;i++)
  
    m[i]=rand()%100;
    n[i]=abs(rand()%200-100);
  
  swap_min(m, n, 10);
  
  getchar();

  return 0;