algorithm/9.html at master · yji234/algorithm · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // 判断一个整数是否是回文数。回文数是指正序（从左向右）和倒序（从右向左）读都是一样的整数。
    // function isPalindrome(x) {
    //   let numList = x.toString().split('');
    //   // console.log(numList);
    //   let newList = [];
    //   for(let i = numList.length-1; i >= 0; i--) {
    //     newList.push(numList[i])
    //   }
    //   // console.log(newList)
    //   if(newList.join('') === x.toString()) {
    //     return true
    //   } else {
    //     return false;
    //   }
    // }


    function isPalindrome(x) {
      let originX = x;
      // console.log(x)
      if(x < 10 && x >= 0) {
        return true
      }
      if(x < 0) {
        x = -x
      }
      let newList = [];
      let remainder;  // 余数
      while (x !== 0) {
        remainder = x % 10;
        newList.push(remainder);
        x = Math.floor(x/10);
      }
      // console.log(newList)
      let newX = newList.join('');
      if(originX < 0) {
        newX = newX + '-'
      }
      // console.log(newX)
      // console.log(originX.toString())
      if(newX === originX.toString()) {
        return true;
      } else {
        return false;
      }
    }

    // console.log(isPalindrome(123))
    // console.log(isPalindrome(121))
    // console.log(isPalindrome(-121))
    // console.log(isPalindrome(10))
    console.log(isPalindrome(0))
    // console.log(isPalindrome(-1))
  </script>
</body>
</html>