402. Remove K Digits | Monotonic Stack | Greedy | Brute Force - Optimal Solution

In this video, I'll talk about how to solve Leetcode 402. Remove K Digits | Monotonic Stack | Greedy | Brute Force - Optimal Solution
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About Me:
I am Aryan Mittal - A Software Engineer in Goldman Sachs, Speaker, Creator & Educator. During my free time, I create programming education content on this channel & also how to use that to grow :)
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#programming #Interviews #leetcode #faang #maang #datastructures #algorithms

[@ARYANMITTAL]

Practice StacK & Monotonic Stack Problems - czcams.com/play/PLEL7R4Pm6EmDSG2vFQN8S04AQfLHC0jR7.html
.
Latest Video on *Hindi Channel* - czcams.com/video/VAP7AZRewCk/video.html

[@AJ-xc3ks]

Bro and we reversing it or using str function so these t.c will be added nn

[@rakeshchahal8330]

class Solution {
public:
string removeKdigits(string nums, int k) {
int n = nums.size();
string ans="";
for(int i=0;inums[i] && k>0)
{
ans.pop_back();
k--;
}
ans.push_back(nums[i]);
}
while(!ans.empty() && k>0)
{
ans.pop_back();
k--;
}
int i=0;
while(ans[i]=='0' && i

[@rishabhgupta6179]

Hi Arayan , I am still not able to understand why removing numbers which are greater than the current number will ensure least possible ans . If possible , do you have an easy explanation.

[@siddharthkachhia4829]

I was try to do it by DP but it gives me TLE😅

[@codingkart245]

idk whether I'm the one who misses his energetic starting this time.

[@satwiktatikonda764]

bro waiting for 100days series :(

[@ARYANMITTAL]

Yaa bro, I’ll planning to bring it in Hindi, so doing preparations for it, will be available on Hindi Channel ❤️❤️

[@Ramgangakumar]

bro your voice [isToLow].

[@user-yl4vp2ox8v]

#include
int rever ( int num)
{
int rev = 0 ;
while(num > 0)
{
int reminder = num%10;
rev = rev*10 + reminder;
num = num/10;
}
return rev ;
}
int main()
{
int num = 125;
int rev = 0 ;
int pos = 1 ;
while (num > 0 )
{
int reminder = num %10;
if (pos == 1 || pos == 4)
{
rev = 10 *rev + reminder;
pos++;
}
pos++;
num = num/10;
}
int rev1 = rever(rev);
printf("%d", rev1);
}

[@user-cv6ed5cb9c]

For me it gave memory limit exceeded for test case 42/43 .
The code was same :
class Solution {
public:
string removeKdigits(string num, int k) {
stack st;
for(auto i:num){
while(!st.empty() && i0 ){
st.pop();k--;
}
st.push(i);
}
while(k>0 && !st.empty())st.pop(),k--;
string ans="";
while(!st.empty()){
ans=ans+st.top();
st.pop();
}
int endIdx=0;
for(int i=ans.length()-1;i>=0;i--){
if(ans[i]!='0'){
endIdx=i;
break;
}
}
ans=ans.substr(0,endIdx+1);
if(ans=="")return "0";
reverse(ans.begin(),ans.end());
return ans;
}
};

[@kabir2190]

same bro 🤣
then i solved it using deque try using deque

[@selfgrowthsigma]

class Solution {
public:
string removeKdigits(string nums, int k) {
int n=nums.size();
if(n==k) return "0";
stackst;
for(int i=0;inums[i] && k>0){
k--;
st.pop();
}
st.push(nums[i]);
}
while(!st.empty() && k>0){
k--;
st.pop();
}
string ans="";
while(!st.empty()){
ans+=st.top();
st.pop();
}
reverse(ans.begin(),ans.end());
for(int i=0;i

[@YashAggarwal-ri6kt]

The problem us u wrote ans=ans+st.top()
Try ans+=st.top()

[@kabir2190]

@@YashAggarwal-ri6kt they are different?😕

[@ARYANMITTAL]

Yes sir, they are different, in cpp += is an overloaded operator for charcters and performs same as push_back() which is O(1) operation, while ans = ans + is an O(n) operation

[@satwiktatikonda764]

Is there any reason for uploading 100 days series in Hindi channel
Ppl like me from South india are also follows ur videos bro

[@tkab1205]

Aapka sound bohot low arha ha

[@khatriiedits3606]

Too long video

[@ganeshsharma5810]

bro can you explain the question in english hindi mix so that we understand the problem more easily

[@RohanSharma-tl9wh]

Aryan please share your leetcode username

[@user-yl4vp2ox8v]

#include
int rever ( int num)
{
int rev = 0 ;
while(num > 0)
{
int reminder = num%10;
rev = rev*10 + reminder;
num = num/10;
}
return rev ;
}
int main()
{
int num = 125;
int rev = 0 ;
int pos = 1 ;
while (num > 0 )
{
int reminder = num %10;
if (pos == 1 || pos == 4)
{
rev = 10 *rev + reminder;
pos++;
}
pos++;
num = num/10;
}
int rev1 = rever(rev);
printf("%d", rev1);
}