Can anyone tell me. how to implement queue using 2 stacks. Specifically, implement the enqueue and dequeuer methods.
it will helpful if you guys tell me in php or JavaScript programming
asked Jun 9, 2016 at 3:03
komal deep singh chahal
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Rather than asking someone to provide you solution, describe what you’ve already tried and the results of any research.user861594– user8615942016-06-09 03:23:31 +00:00Commented Jun 9, 2016 at 3:23
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i know how to di it in c language.. i saw many examples by searching on google... but dont know how to do this in php.... thats why i asked mankomal deep singh chahal– komal deep singh chahal2016-06-09 03:26:46 +00:00Commented Jun 9, 2016 at 3:26
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2 Answers
Here is a personal example, I'm sure it could be more optimized, but it allows for queue dequeue and peek functionality in JS.
function processData(input) {
let stackOne = [];
let stackTwo = [];
let parsableInput = input.split('\n');
for(let i = 1; i < parsableInput.length; i++) {
// handle 1 push
if (parsableInput[i][0] === '1') {
enqueue(stackOne, stackTwo, parsableInput[i].slice(2));
}
// handle 2
if (parsableInput[i] === '2') {
dequeue(stackTwo);
}
// handle 3
if (parsableInput[i] === '3') {
console.log(peek(stackTwo));
}
}
}
function enqueue(stackOne, stackTwo, queuedValue) {
while(stackTwo.length !== 0) {
stackOne.push(stackTwo.pop());
}
stackOne.push(queuedValue);
while(stackOne.length !== 0) {
stackTwo.push(stackOne.pop());
}
}
function dequeue(stackTwo) {
return stackTwo.pop();
}
function peek(stackTwo) {
let stringToBeParsed = stackTwo[stackTwo.length - 1];
let parsedString = stringToBeParsed.slice(0, stringToBeParsed.length);
if (parsedString) {
return parsedString;
} else {
console.log('Error: there is nothing to peek at!');
}
}
Comments
Here is my solution, but it's in C lang.
#include<stdio.h>
#include<stdlib.h>
struct Stack{
int size;
int top;
int *S;
}S1,S2;
void create(struct Stack *st){
st->size=10;
st->top=-1;
st->S=(int *)malloc(st->size*sizeof(int));
}
void push(struct Stack *st, int x){
if(st->top==st->size-1)
printf("\nStack overflow\n");
else
{
st->top++;
st->S[st->top]=x;
}
}
int pop(struct Stack *st){
int x=-1;
if(st->top==-1)
printf("\nStack Underflow\n");
else
{
x=st->S[st->top--]; // post decrement of top
}
return x;
}
int isEmpty(struct Stack *st){
if(st->top==-1)
return 1;
return 0;
}
void enqueue(int x){
push(&S1,x);
}
int dequeue(){
int x=-1;
if(isEmpty(&S2)){
if(isEmpty(&S1)){
printf("Empty Queue!");
return x;
}
else
{
while(!isEmpty(&S1))
push(&S2,pop(&S1));
}
}
return pop(&S2);
}
void display(struct Stack *st){
for(int i=st->top;i>=0;i--)
printf("%d ",st->S[i]);
printf("\n");
}
int main(){
create(&S1);
create(&S2);
enqueue(10);
enqueue(20);
enqueue(30);
enqueue(40);
int deleted_element=dequeue();
printf("Dequeued Element is = %d\n",deleted_element);
display(&S2);
return 0;
}
