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  1. #include <iostream>
  2. #include <bits/stdc++.h>
  3. using namespace std;
  4.  
  5. int cnt_subs(vector<int>&arr){
  6.     int n=arr.size();
  7.     int even=1,odd=0;
  8.     int curr_sum=0;
  9.     int cnt=0;
  10.  
  11.     for(int i=0;i<n;i++){
  12.         curr_sum+=arr[i];
  13.         int p;
  14.         if(curr_sum%2==0){
  15.             p=0;
  16.         }
  17.         else{
  18.             p=1;
  19.         }
  20.  
  21.         if(p==0){
  22.             cnt+=even;
  23.         }
  24.         else if(p==1){
  25.             cnt+=odd;
  26.         }
  27.  
  28.         if(p==0) even++;
  29.         else odd++;
  30.     }
  31.  
  32.     return cnt;
  33. }
  34. int main(){
  35.     int n;
  36.     cin>>n;
  37.     vector<int>arr(n);
  38.     for(int i=0;i<n;i++){
  39.         cin>>arr[i];
  40.     }
  41.     int M=cnt_subs(arr);
  42.     for(int i=0;i<n;i++){
  43.         if(arr[i]%2==0){
  44.             int old=arr[i];
  45.             arr[i]=arr[i]+1;
  46.             int cnt=cnt_subs(arr);
  47.             M=max(M,cnt);
  48.             arr[i]=old;
  49.         }
  50.         else{
  51.             int old=arr[i];
  52.             arr[i]=arr[i]+1;
  53.             int cnt=cnt_subs(arr);
  54.             M=max(M,cnt);
  55.             arr[i]=old;
  56.         }
  57.     }
  58.     cout<<"Number of subarrays of even sum after performing the operation: "<<M<<endl;
  59.     return 0;
  60. }
Success #stdin #stdout 0.01s 5284KB
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stdin
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4
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stdout
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Number of subarrays of even sum after performing the operation: 6
https://ideone.com/7TBvRE
language:
C++ (gcc 8.3)
created:
5 hours ago
visibility:
public

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