1529. Bulb Switcher IV

https://leetcode.com/problems/bulb-switcher-iv

Description

There is a room with n bulbs, numbered from 0 to n - 1, arranged in a row from left to right. Initially, all the bulbs are turned off.

Your task is to obtain the configuration represented by target where target[i] is '1' if the ith bulb is turned on and is '0' if it is turned off.

You have a switch to flip the state of the bulb, a flip operation is defined as follows:

• Choose any bulb (index i) of your current configuration.

• Flip each bulb from index i to index n - 1.

When any bulb is flipped it means that if it is '0' it changes to '1' and if it is '1' it changes to '0'.

Return the minimum number of flips required to form target.

Example 1:

**Input:** target = "10111"
**Output:** 3
**Explanation:** Initial configuration "00000".
flip from the third bulb:  "00000" -> "00111"
flip from the first bulb:  "00111" -> "11000"
flip from the second bulb:  "11000" -> "10111"
We need at least 3 flip operations to form target.

Example 2:

**Input:** target = "101"
**Output:** 3
**Explanation:** "000" -> "111" -> "100" -> "101".

Example 3:

**Input:** target = "00000"
**Output:** 0

Example 4:

**Input:** target = "001011101"
**Output:** 5

Constraints:

• 1 <= target.length <= 105

• target[i] is either '0' or '1'.

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