0926. Flip String to Monotone Increasing - kumaeki/LeetCode GitHub Wiki
0926. Flip String to Monotone Increasing
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 <= 10^5
- s[i] is either '0' or '1'.
class Solution {
public int minFlipsMonoIncr(String s) {
int size = s.length();
// 从左往右, 把所有碰到的0都变为1, 用的次数
int[] left = new int[size + 2];
for(int i = 1; i <= size; i++)
left[i] = left[i - 1] + (s.charAt(i - 1) == '1' ? 1 : 0);
// 从右往左, 把所有碰到的1都变为0, 用的次数
int[] right = new int[size + 2];
for(int i = size; i > 0; i--)
right[i] = right[i + 1] + (s.charAt(i - 1) == '0' ? 1 : 0);
// 对于每个位置,左边都变为0, 右边都变为1的总次数,找最小值
int result = Integer.MAX_VALUE;
for(int i = 0; i <= size; i++)
result = Math.min(result, left[i] + right[i + 1]);
return result;
}
}