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434. Number of Segments in a String

Description

Given a string s, return the number of segments in the string.

A segment is defined to be a contiguous sequence of non-space characters.

 

Example 1:

Input: s = "Hello, my name is John"
Output: 5
Explanation: The five segments are ["Hello,", "my", "name", "is", "John"]

Example 2:

Input: s = "Hello"
Output: 1

 

Constraints:

• 0 <= s.length <= 300
• s consists of lowercase and uppercase English letters, digits, or one of the following characters "!@#$%^&*()_+-=',.:".
• The only space character in s is ' '.

Solutions

Solution 1: String Splitting

We split the string $\textit{s}$ by spaces and then count the number of non-empty words.

The time complexity is $O(n)$, and the space complexity is $O(n)$, where $n$ is the length of the string $\textit{s}$.

Solution 2: Simulation

We can also directly traverse each character $\text{s[i]}$ in the string. If $\text{s[i]}$ is not a space and $\text{s[i-1]}$ is a space or $i = 0$, then $\text{s[i]}$ marks the beginning of a new word, and we increment the answer by one.

After the traversal, we return the answer.

The time complexity is $O(n)$, where $n$ is the length of the string $\textit{s}$. The space complexity is $O(1)$.

• Java
• C++
• Python
• Go
• Php
• TypeScript

• class Solution {
      public int countSegments(String s) {
          int ans = 0;
          for (int i = 0; i < s.length(); ++i) {
              if (s.charAt(i) != ' ' && (i == 0 || s.charAt(i - 1) == ' ')) {
                  ++ans;
              }
          }
          return ans;
      }
  }
  
  
  // Solution 2
  class Solution {
      public int countSegments(String s) {
          int ans = 0;
          for (int i = 0; i < s.length(); ++i) {
              if (s.charAt(i) != ' ' && (i == 0 || s.charAt(i - 1) == ' ')) {
                  ++ans;
              }
          }
          return ans;
      }
  }
  
  

• class Solution {
  public:
      int countSegments(string s) {
          int ans = 0;
          for (int i = 0; i < s.size(); ++i) {
              if (s[i] != ' ' && (i == 0 || s[i - 1] == ' ')) {
                  ++ans;
              }
          }
          return ans;
      }
  };
  
  
  // Solution 2
  class Solution {
  public:
      int countSegments(string s) {
          int ans = 0;
          for (int i = 0; i < s.size(); ++i) {
              if (s[i] != ' ' && (i == 0 || s[i - 1] == ' ')) {
                  ++ans;
              }
          }
          return ans;
      }
  };
  
  

• class Solution:
      def countSegments(self, s: str) -> int:
          ans = 0
          for i, c in enumerate(s):
              if c != ' ' and (i == 0 or s[i - 1] == ' '):
                  ans += 1
          return ans
  
  
  # Solution 2
  class Solution:
      def countSegments(self, s: str) -> int:
          ans = 0
          for i, c in enumerate(s):
              if c != ' ' and (i == 0 or s[i - 1] == ' '):
                  ans += 1
          return ans
  
  

• func countSegments(s string) int {
  	ans := 0
  	for i, c := range s {
  		if c != ' ' && (i == 0 || s[i-1] == ' ') {
  			ans++
  		}
  	}
  	return ans
  }
  
  
  // Solution 2
  func countSegments(s string) int {
  	ans := 0
  	for i, c := range s {
  		if c != ' ' && (i == 0 || s[i-1] == ' ') {
  			ans++
  		}
  	}
  	return ans
  }
  
  

• class Solution {
      /**
       * @param String $s
       * @return Integer
       */
      function countSegments($s) {
          $arr = explode(' ', $s);
          $cnt = 0;
          for ($i = 0; $i < count($arr); $i++) {
              if (strlen($arr[$i]) != 0) {
                  $cnt++;
              }
          }
          return $cnt;
      }
  }
  
  
  // Solution 2
  class Solution {
      /**
       * @param String $s
       * @return Integer
       */
      function countSegments($s) {
          $ans = 0;
          $n = strlen($s);
          for ($i = 0; $i < $n; $i++) {
              $c = $s[$i];
              if ($c !== ' ' && ($i === 0 || $s[$i - 1] === ' ')) {
                  $ans++;
              }
          }
          return $ans;
      }
  }
  
  

• function countSegments(s: string): number {
      return s.split(/\s+/).filter(Boolean).length;
  }
  
  
  // Solution 2
  function countSegments(s: string): number {
      let ans = 0;
      for (let i = 0; i < s.length; i++) {
          let c = s[i];
          if (c !== ' ' && (i === 0 || s[i - 1] === ' ')) {
              ans++;
          }
      }
      return ans;
  }
  
  

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