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回文字符串 / isPalindrome

题目描述

从左往右读和从右往左读是一样的字符串，则认为是一个回文字符串。

Input: ABCDCBA
Ouput: true

Input: EFEF
Ouput: false

Input: ''
Output: true

Code

function isPalindrome(str) {
  if (str === '') return true;
  const len = str.length;
  let left = 0;
  let right = len - 1;
  while (left < right) {
    if (str[left] !== str[right]) {
      return false;
    }
    left++;
    right--;
  }
  return true;
}

Test Cases

const { isPalindrome } = require('../docs/algo/string/palindrome');
describe('isPalindrome', () => {
  it('case1', () => {
    expect(isPalindrome('ABCDCBA')).toBeTruthy();
  });
  it('case2', () => {
    expect(isPalindrome('EFEF')).toBeFalsy();
  });
  it('Test empty string', () => {
    expect(isPalindrome('')).toBeTruthy();
  });
});

jest --testNamePattern=isPalindrome