查找数组中元素

对于任意一个数组，不知道是无序还是有序，查找是否有元素，那比较保险的方法就是遍历。

伪代码

对于任何一个数组：

Write "Please input the sum  "
Read n
Integer number[n]
Write "Enter integer numbers, one per line"
Set position to 0
While(position < n)
    Read in numbers[position]
    Set position to position + 1
Write "Search "
Read search
Set i to 0
Set flag to 0
While(i < n)
    If(search == number[i])
        Write "The number is in the array."
        Set flag to 1
　　　　　Break

If(fiag == 0)
    Write "The number is not in the array."

如果数组有序，那么就会好找不少。这里不妨假设数组number[n]是由小到大排序的，只需将搜索改成改成如下：

Set left to 0
Set right to n - 1
Set middle to (left ADD right) DIV 2
Set flag to 0
While(left < middle && middle < right)
    If(search < number[middle])
        Set right to middle
        Set middle to (left ADD right) DIV 2
    Else If(search > number[middle])
        Set left to middle
        Set middle to (left ADD right) DIV 2
    Else If(search == number[middle])
        Set flag = 1
        Break
If(flag)
    Write "The number is not in the array."
Else If(flag)
    Write "The number is in the array."

采用二分法，能极大提高搜素速度。

这里个人手动走代码测试了一下

 

 

 

 

 

 结果算是比较正确了。就是手动走代码有点累。