Two algorithmic questions about Yang Hui’s triangle and bracket matching

1. Enter a number and determine which row it is in Yang Hui's triangle
Key Points: Two-dimensional array

function fun(item) {
        if(item===1) return 1;        
        var arr = [];        
        for(var i=0;;i++) {
            arr[i] = [];            
            for (var j = 0; j <= i; j++) {                
            if (i == j || j == 0) {
                    arr[i][j] = 1
                } else {
                    arr[i][j] = arr[i - 1][j] + arr[i - 1][j - 1];                    
                    if(arr[i][j] ==item){                        
                    return i+1;
                    }
                }
            }
        }
    }

2. Enter a series of brackets like this:

 function check(str) {
        var arr = str.split(''); // 将传入字符串转化为数组
        var stack = new Array(); // 新建栈，这里我用数组代替
        var aString = '({[]})' ; // 用来匹配的字符串
        var index = -1;          //初始化下标
        for (var i = 0; i < arr.length; i++) {            
        var item = arr[i];            
        if ((index = aString.indexOf(item)) < 3) {   // 将每一项都用aString匹配，下标小于3就是左括号
                // 左括号，入栈
                stack.push(item)
            } else {                //  右括号，栈列表出栈一个元素与之匹配
                var target = stack.pop();                //  如果出栈元素不存在，则这个右括号没有响应匹配的左括号，验证失败
                if (!target) {                    return false
                }                // 取出与 item 对应的左括号与出栈元素匹配，不相等则验证失败
                if (target !== aString.charAt(5-index)) {                    
                return false
                }
            }
        }        //  循环匹配完成后，如果栈列表还有元素，则缺少与之匹配的右括号，验证失败
        if (stack.length) {            
        return false
        }        //  ok
        return true
    }

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