[Python][leetcode 704. Binary Search] basic problem

📕 Problem

https://leetcode.com/problems/binary-search/

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💡 My Solution

This is very basic problem for binary search method. 

# leetcode
# 704. Binary Search

# nums = [-1,0,3,5,9,12]
# target = 9

nums = [-1,0,3,5,9,12]
target = 9

# sort the list first
nums.sort()
star = 0
end = len(nums) - 1
flag = 0
index = 0

while True:
    mid = (star + end)//2
    if nums[mid] == target:
        flag = 1
        index = mid
        break
    elif nums[mid] > target:
        end = mid - 1
    else:
        star = mid + 1
    if end < star:
        flag = 0
        break
if flag == 0:
    # target does not exist
    print(-1)
else:
    print(f"{nums[mid]} exists in nums and its index is {index}")

 

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✔️ TIL (Today I learned)

Becuase I practiced binary search a lot before. This problem was not difficult. Practice makes perfect.  Also It was very helpful to write down and draw the process of algorithm. 

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💻 Answer

 

▷ Final code 

 

class Solution(object):
    def search(self, nums, target):

        # sort the list first
        nums.sort()
        star = 0
        end = len(nums) - 1
        flag = 0
        index = 0

        while True:
            mid = (star + end)//2
            if nums[mid] == target:
                flag = 1
                index = mid
                break
            elif nums[mid] > target:
                end = mid - 1
            else:
                star = mid + 1
            if end < star:
                flag = 0
                break
        if flag == 0:
            # target does not exist
            return - 1
        else:
            # target exist
            return index