搜索算法：线性搜索、二分法

搜索算法：
1.线性搜索：循环遍历，判断是否等于目标值
2.二分法：（需要有序）先定一个起点和终点left,right，当left<right时，取中间值mid，如果目标值小于mid，则right=mid-1,反之亦然

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# 线性搜索 def action1(arr, target):     for i in arr:         if i == target:             print(arr.index(i))   # 二分法 def action2(arr, target):     left, right = 0, len(arr)-1     while left <= right:         mid = (left + right) // 2         if arr[mid] == target:             print(mid)             break         elif arr[mid] < target:             left = mid + 1         else:             right = mid - 1         if __name__ == '__main__':     arr = 'adsyui'     target = 'y'     # 线性搜索     action1(arr, target)     arr = [1, 3, 4, 7, 9]     target = 4     # 二分法     action2(arr, target)