基础排序查找算法

兵临城下 — Fri, 19 Aug 2011 10:28:00 GMT

二分查找：
binarysearch考的比较多，它适用于已经排序的元素中的查找

int binarySearch(int a[],int len,int value)

{
    int low = 0;
    int high = len -1;

    while(low<=high) //注意搜索条件，有可能两者会相等
    {
        int mid = (low+high)/2;
        if(a[mid]==value) return mid;
        else if(a[mid]>value) high = mid -1;
        else low = mid + 1;
    }
    return -1;
}

int main()
{
    int a[] = {1,2,3,4,5,6,7,8,9,10};
    int rec = binarySearch(a,10,4);
    if(rec==-1)
        printf("Not found\n");
    else
        printf("value is found %d \n",rec);
    return 0;
}

快速排序
对冒泡算法的扩展

int partition(int a[],int low,int high)

{
    int temp = a[low];
    while(low<high)
    {
  while(low<high && a[high]>=temp) --high;
        a[low] = a[high];
        while(low<high && a[low]<=temp)  ++low;
        a[high] = a[low];
    }

    a[low] = temp;
    return low;
}


void Qsort(int a[],int begin,int end)
{
    int rec;
    if(begin<end)
    {
        rec = partition(a,begin,end);
        printf("rec is %d\n",rec);
        Qsort(a,begin,rec-1);
        Qsort(a,rec+1,end);
    }
}

int main()
{
    int  a[] = {1,4,0,-3,90,7,9,23};
    Qsort(a,0,7);
    int i =0;
    for(;i<8;i++)
        printf("%d\t",a[i]);

    return 0;
}

兵临城下 2011-08-19 18:28 发表评论

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基础排序查找算法