LeetCode-in-Java
926. Flip String to Monotone Increasing
Medium
A binary string is monotone increasing if it consists of some number of 0’s (possibly none), followed by some number of 1’s (also possibly none).
You are given a binary string s. You can flip s[i] changing it from 0 to 1 or from 1 to 0.
Return the minimum number of flips to make s monotone increasing.
Example 1:
Input: s = “00110”
Output: 1
Explanation: We flip the last digit to get 00111.
Example 2:
Input: s = “010110”
Output: 2
Explanation: We flip to get 011111, or alternatively 000111.
Example 3:
Input: s = “00011000”
Output: 2
Explanation: We flip to get 00000000.
Constraints:
1 <= s.length <= 105s[i]is either'0'or'1'.
Solution
public class Solution {
public int minFlipsMonoIncr(String s) {
if (s == null || s.length() <= 1) {
return 0;
}
final int n = s.length();
int countOnes = 0;
int countFlips = 0;
for (int i = 0; i < n; i++) {
if (s.charAt(i) == '0') {
if (countOnes == 0) {
continue;
} else {
countFlips++;
}
} else {
countOnes++;
}
countFlips = Math.min(countFlips, countOnes);
}
return countFlips;
}
}