leetcode
November 30, 2023

Viiisit [LeetCode] - 392. Is Subsequence

#php#javascript#ruby

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Problem - Is Subsequence

Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., “ace” is a subsequence of “abcde” while “aec” is not).

翻譯蒟蒻

給定兩個字串 s 和 t，如果 s 是 t 的子序列，則返回 true；否則返回 false。例如，”ace” 是 “abcde” 的子序列，而”aec”則不是。換句話說，如果字串 s 的所有字都按照相對順序出現在字串 t 中，即使其中有些字被刪除，仍然視為 s 是 t 的子序列。

Solution - JavaScript

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/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var isSubsequence = function(s, t) {
  let i = 0;
  let j = 0;

  while (i < s.length && j < t.length) {
    if (s[i] === t[j]) {
      // 如果 s 中的字與 t 中的字相等，將 i 往後移動
      i++;
    }
    // 不管是否相等，j 都要往後移動
    j++;
  }

  // 如果 i 走到底，代表 s 中的字都在 t 中出現過
  return i === s.length;
};

Solution - Ruby

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def is_subsequence(s, t)
  i = 0
  j = 0

  while i < s.length && j < t.length
      if s[i] == t[j]
          i += 1
      end
      j += 1
  end
  
  i == s.length
end

Solution - PHP

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function isSubsequence($s, $t) {
  $sLen = strlen($s);
  $tLen = strlen($t);
  $i = 0;
  $j = 0;
  while ($i < $sLen && $j < $tLen) {
      if ($s[$i] == $t[$j]) {
          $i++;
      }
      $j++;
  }
  return $i == $sLen;  
}

LeetCode 傳送門 - Is Subsequence