A string of '0's and '1's is monotone increasing if it consists of some number of '0's (possibly 0), followed by some number of '1's (also possibly 0.)
We are given a string S of '0's and '1's, and we may flip any '0' to a '1' or a '1' to a '0'.
Return the minimum number of flips to make S monotone increasing.
Example 1:
Input: "00110"Output: 1Explanation: We flip the last digit to get 00111.
Example 2:
Input: "010110"Output: 2Explanation: We flip to get 011111, or alternatively 000111.
Example 3:
Input: "00011000"Output: 2Explanation: We flip to get 00000000.