冒泡、二分排序

#include<stdio.h>

void main()
{
    int a[10] = {0};
    int i,j,t;
    printf("input 10 numbers:
");
    for (i = 0; i < 10; i++) {
        scanf("%d", &a[i]);
    }
    printf("
");
    
    for (j = 0; j < 9; j++) {
        for (i = 0; i < 9 - j; i++) {
            if (a[i] > a[i+1]) {
                t = a[i];
                a[i] = a[i+1];
                a[i+1] = t;
            }
        }    
    }
    printf("The sorted numbers are:
");
    for (i = 0; i < 10; i++) {
        printf("%d ", a[i]);
    }
    printf("
");
}

以上是冒泡排序，前提没有要求，测试的数据可以无序。

而二分法一般要求测试数据先排好序，一般是用于插入或查找一个数据。最后如果出现low > high就Over。

二分法如下：

#include<stdio.h>

int main()
{
    int a[10] = {-12, 0, 6, 16, 23, 56, 80, 100, 110, 115};
    int n, low, high, mid, found;
    low = 0;
    high = 9;
    found = 0;
    printf("Input a number to be searched:");
    scanf("%d", &n);
    
    while (low <= high) {
        mid = (low + high)/2;
        if (n == a[mid]) {
            found = 1;
            break;
        }
        else if (n > a[mid]) {
            low = mid + 1;
        }
        else {
            high = mid - 1;
        }
    }
    
    if (1 == found) {
        printf("The index of %d is %d
", n, mid);
    }
    else {
        printf("There's no %d
", n);
    }
    
    return 0;
}