冒泡、二分排序

 1 #include<stdio.h>
 2 
 3 void main()
 4 {
 5     int a[10] = {0};
 6     int i,j,t;
 7     printf("input 10 numbers:\n");
 8     for (i = 0; i < 10; i++) {
 9         scanf("%d", &a[i]);
10     }
11     printf("\n");
12     
13     for (j = 0; j < 9; j++) {
14         for (i = 0; i < 9 - j; i++) {
15             if (a[i] > a[i+1]) {
16                 t = a[i];
17                 a[i] = a[i+1];
18                 a[i+1] = t;
19             }
20         }    
21     }
22     printf("The sorted numbers are:\n");
23     for (i = 0; i < 10; i++) {
24         printf("%d ", a[i]);
25     }
26     printf("\n");
27 }

以上是冒泡排序，前提沒有要求，測試的數據能夠無序。

而二分法通常要求測試數據先排好序，通常是用於插入或查找一個數據。最後若是出現low > high就Over。

二分法以下：

 1 #include<stdio.h>
 2 
 3 int main()
 4 {
 5     int a[10] = {-12, 0, 6, 16, 23, 56, 80, 100, 110, 115};
 6     int n, low, high, mid, found;
 7     low = 0;
 8     high = 9;
 9     found = 0;
10     printf("Input a number to be searched:");
11     scanf("%d", &n);
12     
13     while (low <= high) {
14         mid = (low + high)/2;
15         if (n == a[mid]) {
16             found = 1;
17             break;
18         }
19         else if (n > a[mid]) {
20             low = mid + 1;
21         }
22         else {
23             high = mid - 1;
24         }
25     }
26     
27     if (1 == found) {
28         printf("The index of %d is %d\n", n, mid);
29     }
30     else {
31         printf("There's no %d\n", n);
32     }
33     
34     return 0;
35 }