C程式設計輔導：ECE222 Vectors And Matrices

Requirement

In this lab, each student is to write a program that allows the user to manipulate the entries in ​​vector​​, or in a ​​matrix​​. The program should keep track of one vector of variable length, and one matrix of exactly 4x4 size. The program should enter a loop, displaying a set of options (given below). Once the user selects an option, the program should display the vector (or matrix, as appropriate) before and after the operation chosen by the user. For example, if the user selects “reverse vector” and the current vector is [-3 0 2 5] then the program should display:

input  
-3 0 2 5  
reversed  
5 2 0 -1
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The program should run until the user selects an option to quit.

The program must use the following structure definitions.

struct vector {
  float *data;
  int    size;
};

struct matrix {
  struct vector rows[4];
};
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Analysis

Vectors和Matrices，​​矢量​​和​​矩陣​​，也稱一維和二維​​數組​​。屬于C語言很常見的資料結構。本題要實作的是矢量的反轉，以及矩陣的轉置。

反轉和轉置需要用到排序算法，這裡我們采用​​Quicksort​​，也就是​​快速排序​​。

Tips

int parition(struct vector *vec, int left, int right) {
  float piovt, temp;
  int i, j;
  piovt = *(vec[left]);
  i = left;
  j = right + 1;

  while (1) {
    do {
      ++i;
    } while (*(vec[i]) <= piovt && i <= right);
    do {
      --j;
    } while (*(vec[j]) > piovt);
    if (i >= j) {
      break;
    }
    temp = *(vec[i]);
    *(vec[i]) = *(vec[j]);
    *(vec[j]) = temp;
  }
  temp = *(vec[left]);
  *(vec[left]) = *(vec[right]);
  *(vec[right]) = temp;
  return j;
}
 
void quick_sort(struct vector *vec, int left, int right) {
  int i;
  if (left < right) {
    i = partition(vec, left, right);
    quick_sort(vec, left, right - 1);
    quick_sort(vec, i + 1, right);
  }
}
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