Updated #1

Author: codewithdev

21- Hashing/CheckifSubarrayWithSumZero.cpp

@@ -0,0 +1,30 @@
+#include<bits/stdc++.h>
+using namespace std;
+bool checkifSubarraySumZero(int *arr, int n){
+   unordered_set<int>s;
+   int pre=0;
+   for(int i=0;i<n;i++){
+   	pre+=arr[i];
+   	if(pre==0 or s.find(pre)!= s.end()){
+   		return true;
+   	}
+   	s.insert(pre);
+   }
+   return false; 
+}
+int main(int argc, char const *argv[]){
+    int n;
+    cin>>n;
+    int *arr= new int[n];
+    for(int i=0;i<n;i++){
+    	cin>>arr[i];
+    }
+    bool b= checkifSubarraySumZero(arr,n);
+    if(b==0){
+    	cout<<"No"<<endl;
+    }
+    else{
+    	cout<<"yes"<<"\n";
+    }
+    return 0;
+}

21- Hashing/longestSubarraywithSumZero.cpp

@@ -0,0 +1,37 @@
+#include<bits/stdc++.h>
+using namespace std;
+int checkIfSubarraySumZero(int *arr, int n){
+	unordered_map<int,int>mp;
+    int pre=0;
+    int len=0;
+    for(int i=0;i<n;i++){
+    	pre+= arr[i];
+    	if(arr[i]==0 and len==0){
+    		len=1;
+    	}
+    	if(pre=0){
+    		len= max(len,i+1);
+    	}
+    	if(mp.find(pre)!=mp.end()){
+    		len= max(len,i-mp[pre]);
+    	}
+    	else{
+    		mp[pre]=i;
+    	}
+    }
+    return len;
+}
+
+int main(){
+
+	int n;
+	cin>>n;
+	int *arr= new int[n];
+	for(int i=0;i<n;i++){
+		cin>>arr[i];
+	}
+	int b= checkIfSubarraySumZero(arr,n);
+	cout<<b<<endl;
+	return 0;
+
+}