Reverse a Sentence using Stacks | Stack Challenge | C++ Placement Course | Lecture 23.2

Notes of this Lecture:

[aayushvyas]

T(n) = O(n) solution below
string sentence = "Hey, how are you doing?";
int i=0;
string temp = " ";
stack <string> s;

if(sentence[i]==' ' or sentence[i]=='\0'){
s.push(temp);
temp = "";
}
temp = temp + sentence[i];
i++;
}
while(!s.empty()){
cout << s.top();
s.pop();
}

[snehilsinha]

Bhaiaya Stack using Linked List ka video miss ho gaya kya ? Kaha par hai ?

[chirag-sgkd]

0:45 Stack implementation using linked list kab hua ??

[ritikprasad]

Where is implementation of stack using linked list ??

[webseriesworld]

For Some persons who is thinking that mam is doing this question in more time complexity
Then guys you are wrong
Take a pen and paper and visualise mam code then you get to know the value of i which we are is the increment vallue of i thats why this code is running same as in one loop or using two loops !!!!

[sachinbairi]

Mujhe janna hai stack ka implementation kab kiya linked list mai ???

[saketkashyap]

At 3:23, I got the point that here we are iterating over the string unless we encounter a space but I didn't understand how this while loop is working and what's the need of i<s.length()

[akashrathod]

Reverse a sentence in "O(n)" time complexity....


void reverseSentence(string s){
stack<string> st;
string word = "";

for (int i=0; i<s.length(); i++){
if (s[i] == ' '){
st.push(word);
word = "";
i++;
}
word += s[i];
}
st.push(word);

while (!st.empty()){
cout << st.top() << " ";
st.pop();
}
cout << endl;
}

Please let me know if you have better approach than this....
And is this program correct or need any modification....
Thank you!

[psychoticgamer]

string s = "hey, how are you doing?" ;
int a = s.length();
while (a--) {
cout<<s[a] ;
}

[webseriesworld]

// We can used one loop also but it saves the character by character
// so we have to make a character array

StackADT* st = new StackADT();

string str = "i am Gourav Khurana";
for(int i = 0; i < str.length(); i++){
st->push(str[i]);
}

string rev;

while(!st->empty()){
char ch = st->top();
rev = rev + ch;
st->pop();
}

cout << rev << endl;

[atulraj]

why don't you upload notes of the lectures ?

[II_xD_II]

std::reverse(Sentence.begin(), Sentence.end());

😳

[toxicboy]

Best way of learning


Thank You sooo much

[sunnykakrani]

ALTERNATIVE CODE:

#include <bits/stdc++.h>
using namespace std;
void solve(string s)
{
stack<string>st;
string words="";
for(int i=0;i<s.size();i++)
{
if(s[i]!=' ')
words=words+s[i];
else
{
st.push(words);
words="";
}
}
st.push(words);
while(!st.empty()){

cout<<st.top()<<endl;
st.pop();
}

}
int main() {

string s="hello what are you doing";
solve(s);
}

[devansh]

Link list jb pdhaya gya tha tb insert at head and delete at head pdhaya gya tha..
Whi hota h push pop🙂
There us no need for specific video of implementation of stack using ll

[tushardixit]

i think in while condition (i<s.length() would come first then s.charAt(i)!=' ')

[mdanishossain]

void solve(string &str) {
stack<char> st;

for(const auto &ch : str) {
if(ch != ' ') st.push(ch);
else {
while(!st.empty()) {
putchar(st.top());
st.pop();
}

putchar(' ');
}
}

while(!st.empty()) {
putchar(st.top());
st.pop();
}

}

[pMuhammadJawadKhan]

where is stack using linked list video ? didi app nay Stack LL wali video upload nh ki ?

[nandyxotaku]

I understand this code, thanks for explaining this :)

[faizahmad]

stack<string> st
why this line has used in the code?