javascript - JS中的罗马到整数为什么它只转换第一个字符

Question

我尝试解决 Leedcode 问题 13，问题是给定一个罗马数字，将其转换为整数。(输入保证在 1 到 3999 的范围内。) 这是我下面的代码，我想知道为什么它只将罗马数字中的第一个字符转换为整数？

var romanToInt = function(s) {
  var result = 0;
  if (s == null) {
    result = 0;
  }
  var myMap = new Map();
  myMap.set('I', 1);
  myMap.set('V', 5);
  myMap.set('X', 10);
  myMap.set('L', 50);
  myMap.set('C', 100);
  myMap.set('D', 500);
  myMap.set('M', 1000);

  var len = s.length;
  for (var i = 0; i < len; i++) {
    if (myMap.get(s.charAt(i)) < myMap.get(s.charAt(i + 1))) {
      result -= myMap.get(s.charAt(i))
    } else {
      result += myMap.get(s.charAt(i))
    }
    return result;
  };
}

console.log(romanToInt('VI'));
console.log(romanToInt('V'));
console.log(romanToInt('VII'));

Answer 1

因为

return result;

在一次迭代后结束循环。将其向下移动一行。而且，如果您进行适当的格式化，则根本不会犯此类错误；)

const values = new Map([
  ['I', 1],
  ['V', 5],
  ['X', 10]
  /*....*/
]);

function romanToInt(string) {
  let result = 0,
    current, previous = 0;
  for (const char of string.split("").reverse()) {
    current = values.get(char);
    if (current >= previous) {
      result += current;
    } else {
      result -= current;
    }
    previous = current;
  }
  return result;
}

console.log(romanToInt('I'));
console.log(romanToInt('II'));
console.log(romanToInt('III'));
console.log(romanToInt('IV'));
console.log(romanToInt('V'));
console.log(romanToInt('VI'));
console.log(romanToInt('VII'));
console.log(romanToInt('VIII'));
console.log(romanToInt('IX'));
console.log(romanToInt('X'));
console.log(romanToInt('XI'));
console.log(romanToInt('XII'));
console.log(romanToInt('XIII'));
console.log(romanToInt('XIV'));
console.log(romanToInt('XV'));
console.log(romanToInt('XVI'));
console.log(romanToInt('XVII'));
console.log(romanToInt('XVIII'));
console.log(romanToInt('XIX'));
console.log(romanToInt('XX'));