javascript-stack-tree

javascript-stack-tree.js

var tree = [
    {
        val: 1, 
        next: [
            {val: 2, next: null},
            {val: 3, next: [{val: 4, next: null}]}
        ]
    }
];
    
var stack = [tree];

while(stack.length) {
    var subTree = stack.pop();
    for (var i = 0; i < subTree.length; i++) {
        var sub = subTree[i];
        sub.next && stack.push(sub.next);
        
        console.log(sub.val);
    }
}


////

var s = '(({}[][])[]){}';
var i = 1;
var stack = [];

stack.push(s[0]);

var isValid = function(s) {
  while(s[i]) {
    
    var cur = s[i];
    var last = stack[stack.length - 1];
    
    if(
      (last === '(' && cur === ')') ||
      (last === '{' && cur === '}') ||
      (last === '[' && cur === ']')
    ) {
      stack.pop(); 
    } else {
      stack.push(cur);
    }

    i++;
  }
  
  return stack.length === 0;
}

console.log(isValid(s));