leetcode 316栈去除重复数字，两种写法有什么区别呢

316. 去除重复字母 - 力扣（LeetCode）

可以通过验证

var removeDuplicateLetters = function (s) {
    let stack = []
    let index = -1;
    //++index
    while (++index < s.length) {
        if (stack.includes(s[index])) continue;
        while (
            stack.length &&
            stack[stack.length - 1] > s[index] &&
            s.includes(stack[stack.length - 1], index)
        ) {
            stack.pop();
        }
        stack.push(s[index]);
    }
    return stack.join("");
};

不能通过验证

var removeDuplicateLetters = function (s) {
    let stack = []
    let index = 0;
    //index从0开始，自增写在while里
    while (index < s.length) {
        if (stack.includes(s[index])) continue;
        while (
            stack.length &&
            stack[stack.length - 1] > s[index] &&
            s.includes(stack[stack.length - 1], index)
        ) {
            stack.pop();
        }
        stack.push(s[index]);
        index++；
    }
    return stack.join("");
};