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926. Flip String to Monotone Increasing 👍

  • Time: $O(|\texttt{s}|)$
  • Space: $O(1)$
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class Solution {
 public:
  int minFlipsMonoIncr(string s) {
    vector<int> dp(2);

    for (const char c : s) {
      const int temp = dp[0] + (c == '1');
      dp[1] = min(dp[0], dp[1]) + (c == '0');
      dp[0] = temp;
    }

    return min(dp[0], dp[1]);
  }
};

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class Solution {
  public int minFlipsMonoIncr(String s) {
    int[] dp = new int[2];

    for (final char c : s.toCharArray()) {
      final int temp = dp[0] + (c == '1' ? 1 : 0);
      dp[1] = Math.min(dp[0], dp[1]) + (c == '0' ? 1 : 0);
      dp[0] = temp;
    }

    return Math.min(dp[0], dp[1]);
  }
}

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class Solution:
  def minFlipsMonoIncr(self, s: str) -> int:
    dp = [0] * 2

    for c in s:
      dp[0], dp[1] = dp[0] + (c == '1'), min(dp[0], dp[1]) + (c == '0')

    return min(dp)