Find Common Characters | Simple Dry Run | Leetcode 1002 | codestorywithMIK

This is the 41st Video of our Playlist "Leetcode Easy : Popular Interview Problems" by codestorywithMIK

In this video we will try to solve a good practice Array+String+Map problem : Find Common Characters | Simple Dry Run | Leetcode 1002 | codestorywithMIK

I will explain the intuition so easily that you will never forget and start seeing this as cakewalk EASYYY.
We will do live coding after explanation and see if we are able to pass all the test cases.
Also, please note that my Github solution link below contains both C++ as well as JAVA code.

Problem Name : Find Common Characters | Simple Dry Run | Leetcode 1002 | codestorywithMIK
Company Tags : will update soon

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Summary :
We need to find the common characters in a list of strings. Here's a summary of the approach :

fillCountArray Method: This helper method takes a string and an array of 26 integers (representing counts for each letter of the alphabet). It increments the counts for each character in the string.

commonChars Method:

Initialization: The method initializes a vector of strings (result) to store the common characters and an integer array count of size 26 to keep track of character frequencies in the first word.
Count Update: It calls fillCountArray on the first word to populate count. Then, for each subsequent word, it uses a temporary count array temp to store character frequencies.
Frequency Comparison: For each character, it updates count to the minimum frequency of that character between the current count and temp.
Result Construction: Finally, it iterates over the count array, and for each non-zero count, it adds the corresponding character to the result the number of times it appears.
Return: The method returns the vector of common characters.

In essence, the solution identifies the minimum frequency of each character across all words and constructs the list of common characters based on these frequencies.

✨ Timelines✨
00:00 - Introduction

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[shivamsingh-mimn]

i just woke and tried the pod of leetcode..but i could not able to solve..so i was waiting for your video .Again You Made my morning....thnku bhaiya

[shibainu]

OMG I solved the question on my own and my code is ditto same as your.

[nerduser]

guess what been trying this problem from yesterday

crazy that IT came as potd today


crazy^2 that you made a video about it

xd

[DevOpskagyaan]

I think this could have been marked MEDIUM
Its a good one. Thanks for explaining so well

[utkarshsahay]

class Solution {
public:
vector<string> commonChars(vector<string>& words) {
vector<int> cnt(26, 0);
vector<string> ans;
for(int i = 0;i < words[0].size();i++){
cnt[words[0][i] - 'a']++;
}
for(int i = 1; i < words.size();i++){
string s = words[i];
vector<int> cnt1(26, 0);
for(char ch : s){
cnt1[ch-'a']++;
}
for(int j = 0; j < 26; j++){
cnt[j] = min(cnt[j], cnt1[j]);
}
}
for(int i = 0;i < 26;i++){
int no = cnt[i];
while(no--) ans.push_back(string(1, 'a'+i));
}
return ans;
}
};❤❤

[unknown]

class Solution {
public:
vector<string> commonChars(vector<string>& words) {
int n=words.size();
vector<int> freq(26, 0);
for(auto ch:words[0]) freq[ch-'a']++;
for(int i=1;i<words.size();i++)
{
vector<int> lf(26, 0);
for(char ch: words[i])
{
lf[ch-'a']++;
}
for(char ch='a';ch<='z';ch++)
{
freq[ch-'a']= min(freq[ch-'a'], lf[ch-'a']);
}
}
// for(auto it: freq){
// cout<<it<<", ";
// }
vector<string> v;
for(int i=0;i<26;i++)
{
int f=freq[i];
char ch='a'+i;
string s="";
s+=ch;
while(f--)
{
v.push_back(s);
}
}
return v;
}
};

[gauravkumar]

bhaiya please segment tree sikha do pls, 1 saal se try kr raha hun sikhne ka aap hi sikha skte ho.
ek 3-4 ghnte ki video bna do, 5-6 questions krwa do along with basic code, please bhaiya

[kumarashutosh-pn]

congrats sir for 50k subs. i hope the count will keep going. please take a glance on gfg potd today's as well. a good prefix sum question.

[AdityaGupta-swzr]

bhaiya gfg ka potd aur start kardo plz plz
Thanks in advance❤❤

[PANKAJKUMAR-nxkv]

please bro explain :- 474. Ones and Zeroes question

[pokeindia]

Bhaiya please longest valid parantheses q ka video laiye important q h interview k liye

[sunilsarode]

class Solution {
public:
vector<string> commonChars(vector<string>& words) {

int n=words.size();

vector<string> ans;

for(int i=0;i<26;i++){

char ch=i+'a';
int charCount=INT_MAX;
for(auto x:words){
int c=0;
for(int j=0;j<x.size();j++){
if(ch ==x[j]){
c++;
}
}
charCount=min(charCount, c);
}

if(charCount!=INT_MAX){
for(int j=0;j<charCount;j++){
string str="";
str.push_back(ch);
ans.push_back(str);
}
}

}

return ans;
}
};

[aizadiqbal]

I wrote this solution on my own
strangely this also passed with 4 ms only


class Solution {
public List<String> commonChars(String[] words) {
int n = words.length;
List<String> ans = new ArrayList<>();

int[][] freq = new int[n][26];

for(int i=0;i<n;i++){
String str = words[i];

for(int j=0;j<str.length();j++){
char ch = str.charAt(j);

}
}
char ch='a';

for(int i=0;i<26;i++){
int min=Integer.MAX_VALUE;
boolean hasChar=true;
for(int j=0;j<n;j++){
if(freq[j][i]==0){
hasChar=false;
}
else{
min=Math.min(min, freq[j][i]);
}
}
if(hasChar){
while(min>0){
ans.add(String.valueOf(ch));
min--;
}
}
ch++;
}

return ans;
}
}

[shivanshishrivastava]

sir please put the solution of leetcode 3122 .I am stuck with this problem

[Manjot_singh]

bhaiya apny ye konsa function use kiya in line 31

[nishantthakur]

bhai or to thik hai pr more pr click krne pr github ka link or whatapp ka link nhi aa rha

[Avatar]

what is the problem with this code :




class Solution {
public:
void fillcount(string &word, int count[26])
{
for(char &c: word)
{
count[c-'a']++;

}
}
vector<string> commonChars(vector<string>& words) {
vector<string>result;
int n=words.size();
int count[26]={0};

fillcount(words[0], count);

for(int i=1;i<n;i++)
{
int temp[26]={0};
fillcount(words[i], temp);
for(int j=0;j<26;j++)
{
count[j]=min(count[j], temp[j]);

}
}


for(int i=0;i<26;i++)
{
if(count[i]!=0)
{
result.push_back(string(1, i+'a'));
}
}
return result;
}
};

[nish]

BRO PLEASE ANSWER THIS QUESTION QUESTION IS IF WE CAN FORM TARGET STRING FROM ARRYA ELEMENTS
import java.util.ArrayList;

public class Solution {
static ArrayList<ArrayList<String>> res = new ArrayList<>(); // Not used in this version

public static void main(String[] args) {
String[] arr = {"os", "mn", "pqr", "qr"};
String t = "pqros"; //THIS SHOULD RETURN TRUE BCOZ PQR+OS is forming target but it is giivng false should return true technically
String sofar = "";
ArrayList<String> l = new ArrayList<>();
System.out.println(canconst(arr, t, sofar, 0, l));
}

public static boolean canconst(String[] arr, String t, String sofar, int idx, ArrayList<String> l) {
if(sofar.equals(t))
{
return true;
}
if (idx >= arr.length) {
return false;
}
// Try appending each string from arr to sofar and recursively check
if (canconst(arr, t, sofar + arr[idx], idx+1, l)) {
return true;
}
return canconst(arr, t, sofar, idx + 1, l);
}
}
//THIS SHOULD RETURN TRUE BCOZ PQR+OS is forming target but it is giivng false should return true technically
this code is only giivng correct output if the we are checking the idx elements sequence wise why so please answer what changes should i make in my code so that it works
galti pakad nai aa rahi please help bhai do ghante ho gaye hit and trial kar raha hu doubt clear kardo aisa kyu horaha hai pLEASE DO REPLY ITS A REQUEST

[Mohit-fehx]

any other method of this question to solve???

[rohitaggarwal]

This is definitely not a easy question