# Longest Subarray of Given Sum

Sat Jul 02 2022 04:55:43 GMT+0000 (UTC)

Saved by @BRIJESH20 #c++

```// Longest Subarray for given sum

#include<bits/stdc++.h>
using namespace std ;

int marLen(int a[], int n, int sum)
{
unordered_map<int, int> m ; vector <int> v ; vector <int> v1 ;
int pre_sum = 0 ; int res = 0 ; cout << "res = " ;
for(int i=0; i<n; i++){
pre_sum += a[i] ; v.push_back(pre_sum) ; v1.push_back(pre_sum - sum) ;
if(pre_sum == sum) res = i+1 ;

if(m.find(pre_sum) == m.end())
m.insert(make_pair(pre_sum, i)) ;

if(m.find(pre_sum-sum) != m.end())
res = max(res, i-m[pre_sum-sum]) ;

cout << res << " " ;
} cout << endl ;
for(int x : v) cout << x << "  " ;
cout << endl ;
for(int x : v1) cout << x << "  " ;
cout << endl ;
return res ;
}

int main()
{

int n ; cin >> n ; int a[n] = {0} ;
int sum ; cin >> sum ;
for(int i=0; i<n; i++) cin >> a[i] ;

cout << marLen(a, n, sum) << endl ;

return 0 ;
}

/* Input -- 8 4
8 3 1 5 -6 6 2 2

Output --
res = 0 0 2 2 2 2 2 4
8  11  12  17  11  17  19  21
4  7  8  13  7  13  15  17
4

*/

```
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Longest Subarray of Given Sum res = max(res, i-m[pre_sum-sum])