问题3，最长公共不重复字符串貌似有更简单的解法

```js
function solve(str) {
	var maxStr = '',
	    tmpStr = '';

	var hashed = {};
	for (const c of str) {
		if (!hashed[c]) {
			hashed[c] = true;
			tmpStr += c;
		} else {
			if (tmpStr.length > maxStr.length) {
				maxStr = tmpStr;
				tmpStr = c;
			}
		}
	}

	return maxStr;
}
```