I've been trying to understanding this part of the code:
if(stack.length > 0 && map[stack[stack.length - 1]] === s[i])
at line 9. What does the "map[stack[stack.length-1]]" mean? At first I thought the map is an object, but I think you are supposed to add " " mark around the properties. Is map a data structure? if it is, How can I use this data structure?
var stack = [];
var len = s.length;
var map = {
'(': ')',
'[': ']',
'{': '}',
};
for(var i = 0; i<len; i++){
if(stack.length > 0 && map[stack[stack.length - 1]] === s[i]) {
stack.pop();
}else{
stack.push(s[i]);
}
}
return stack.length === 0;
};
Map is an object and
map[stack[stack.length - 1]]
is the property of 'map' wich key is the value of the last element of the array stack. As properties of an object can be accessed both these ways
const object = {
"property1" : value1,
"property2" : value2,
}
object.property1 == object['property1']; // is true
object.property2 == object['property2']; // is also true