Interview Classic 150 Questions P58 Length of Last Word

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Timeline

timeline

2025-10-12

init

string

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Problem:

P58 Length of Last Word

https://leetcode.cn/problems/length-of-last-word/description/?envType=study-plan-v2&envId=top-interview-150

Directly find two positions: the first is the end of the last word, the second is the position before the start of the last word. Note that start should be initialized to -1 to handle the case s = ‘a’.

#include <string>
using std::string;

class Solution {
public:
  int lengthOfLastWord(string s) {
    int len = s.size();
    int i = len - 1;
    int end = 0, start = -1;

    while (i >= 0) {
      if (std::isalpha(s[i])) {
        end = i;
        break;
      }
      i--;
    }
    
    while (i >= 0) {
      if (!std::isalpha(s[i])) {
        start = i;
        break;
      }
      i--;
    }

    return end - start;

  }
};