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Formatted question description: https://leetcode.ca/all/1422.html

1422. Maximum Score After Splitting a String (Easy)

Given a string s of zeros and ones, return the maximum score after splitting the string into two non-empty substrings (i.e. left substring and right substring).

The score after splitting a string is the number of zeros in the left substring plus the number of ones in the right substring.

 

Example 1:

Input: s = "011101"
Output: 5 
Explanation: 
All possible ways of splitting s into two non-empty substrings are:
left = "0" and right = "11101", score = 1 + 4 = 5 
left = "01" and right = "1101", score = 1 + 3 = 4 
left = "011" and right = "101", score = 1 + 2 = 3 
left = "0111" and right = "01", score = 1 + 1 = 2 
left = "01110" and right = "1", score = 2 + 1 = 3

Example 2:

Input: s = "00111"
Output: 5
Explanation: When left = "00" and right = "111", we get the maximum score = 2 + 3 = 5

Example 3:

Input: s = "1111"
Output: 3

 

Constraints:

• 2 <= s.length <= 500
• The string s consists of characters '0' and '1' only.

Related Topics:
String

Solution 1.

zero and one are the counts of 0s in left and 1s in right.

First compute the count of all 1s as one. Then for each i in range [0, N - 2], increment zero if s[i] == '0' and decrement one if s[i] == '1'. The maximum zero + one is the result.

// OJ: https://leetcode.com/problems/maximum-score-after-splitting-a-string
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int maxScore(string s) {
        int one = 0, zero = 0, ans = 0;
        for (char c : s) one += c == '1';
        for (int i = 0; i < s.size() - 1; ++i) {
            char c  = s[i];
            zero += c == '0';
            one -= c == '1';
            ans = max(ans, zero + one);
        }
        return ans;
    }
};

• Java
• C++
• Python
• Go
• TypeScript
• RenderScript

• class Solution {
      public int maxScore(String s) {
          int length = s.length();
          int ones = 0;
          for (int i = 0; i < length; i++) {
              char c = s.charAt(i);
              if (c == '1')
                  ones++;
          }
          int maxScore = 0;
          int leftZeros = 0, rightOnes = ones;
          for (int i = 1; i < length; i++) {
              char lastC = s.charAt(i - 1);
              if (lastC == '0')
                  leftZeros++;
              else
                  rightOnes--;
              int score = leftZeros + rightOnes;
              maxScore = Math.max(maxScore, score);
          }
          return maxScore;
      }
  }
  
  ############
  
  class Solution {
      public int maxScore(String s) {
          int t = 0;
          if (s.charAt(0) == '0') {
              t++;
          }
          for (int i = 1; i < s.length(); ++i) {
              if (s.charAt(i) == '1') {
                  t++;
              }
          }
          int ans = t;
          for (int i = 1; i < s.length() - 1; ++i) {
              t += s.charAt(i) == '0' ? 1 : -1;
              ans = Math.max(ans, t);
          }
          return ans;
      }
  }
  

• // OJ: https://leetcode.com/problems/maximum-score-after-splitting-a-string
  // Time: O(N)
  // Space: O(1)
  class Solution {
  public:
      int maxScore(string s) {
          int one = 0, zero = 0, ans = 0;
          for (char c : s) one += c == '1';
          for (int i = 0; i < s.size() - 1; ++i) {
              char c  = s[i];
              zero += c == '0';
              one -= c == '1';
              ans = max(ans, zero + one);
          }
          return ans;
      }
  };
  

• class Solution:
      def maxScore(self, s: str) -> int:
          ans = t = (s[0] == '0') + s[1:].count('1')
          for i in range(1, len(s) - 1):
              t += 1 if s[i] == '0' else -1
              ans = max(ans, t)
          return ans
  
  
  

• func maxScore(s string) int {
  	t := 0
  	if s[0] == '0' {
  		t++
  	}
  	n := len(s)
  	for i := 1; i < n; i++ {
  		if s[i] == '1' {
  			t++
  		}
  	}
  	ans := t
  	for i := 1; i < n-1; i++ {
  		if s[i] == '0' {
  			t++
  		} else {
  			t--
  		}
  		ans = max(ans, t)
  	}
  	return ans
  }
  
  func max(a, b int) int {
  	if a > b {
  		return a
  	}
  	return b
  }
  

• function maxScore(s: string): number {
      const n = s.length;
      let res = 0;
      let score = 0;
      if (s[0] === '0') {
          score++;
      }
      for (let i = 1; i < n; i++) {
          if (s[i] === '1') {
              score++;
          }
      }
      res = Math.max(res, score);
      for (let i = 1; i < n - 1; i++) {
          if (s[i] === '0') {
              score++;
          } else if (s[i] === '1') {
              score--;
          }
          res = Math.max(res, score);
      }
      return res;
  }
  
  

• impl Solution {
      pub fn max_score(s: String) -> i32 {
          let n = s.len();
          let mut res = 0;
          let mut score = 0;
          let bs = s.as_bytes();
          if bs[0] == b'0' {
              score += 1;
          }
          for i in 1..n {
              if bs[i] == b'1' {
                  score += 1;
              }
          }
          res = res.max(score);
          for i in 1..n - 1 {
              if bs[i] == b'0' {
                  score += 1;
              } else if bs[i] == b'1' {
                  score -= 1;
              }
              res = res.max(score);
          }
          res
      }
  }
  
  

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