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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <cmath>
  4. #include <algorithm>
  5. #include <bits/stdc++.h>
  6. #include <set>
  7. #include <ext/pb_ds/assoc_container.hpp>
  8. #include <ext/pb_ds/tree_policy.hpp>
  9. #include <map>
  10. #define ll long long
  11. using namespace __gnu_pbds;
  12. using namespace std;
  13. template <class T>
  14. using ordered_set = tree<T , null_type , less<T> , rb_tree_tag , tree_order_statistics_node_update>;
  15. template <class T>
  16. using ordered_set1 = tree<T , null_type , greater<T> , rb_tree_tag , tree_order_statistics_node_update>;
  17. // less<T>/greater<T> = ascending/descending.
  18. // less_equal<>/greater_equal<> for ordered multiset
  19. // ordered_multiset note : s.find(), s.erase() don't work + s.upper_bound() and s.lower_bound() swap jobs;
  20. void fastIO(void) {
  21.     ios_base::sync_with_stdio(false);
  22.     cin.tie(NULL);
  23.     cout.tie(NULL);
  24. }
  25. int main() {
  26.     fastIO();
  27.     ll n,sum; cin>>n>>sum;
  28.     vector<ll> v(n);
  29.     vector<ll> v2(n);
  30.     for (ll i = 0; i<n; i++) {
  31.         cin>>v[i];
  32.         v2[i]=v[i];
  33.     }
  34.     sort(v.begin(),v.end());
  35.     ll l=0,r=n-1; bool flag = 0;
  36.  
  37.     while (l<r) {
  38.         if (v[l]+v[r]>sum) {
  39.             r--;
  40.         }
  41.         else if (v[l]+v[r]<sum) {
  42.             l++;
  43.         }
  44.         else {
  45.             flag = 1;
  46.             break;
  47.         }
  48.     }
  49.  
  50.     if (flag) {
  51.         ll realL,realR;
  52.         for (ll i = 0; i<n; i++) {
  53.             if (v2[i]==v[l]) {
  54.                 realL=i;
  55.                 break;
  56.             }
  57.         }
  58.         for (ll i = 0; i<n; i++) {
  59.             if (v2[i]==v[r]) {
  60.                 realR=i;
  61.                 break;
  62.             }
  63.         }
  64.         cout<<realL+1<<' '<<realR+1;
  65.     }
  66.     else {
  67.         cout<<"IMPOSSIBLE";
  68.     }
  69. }
Success #stdin #stdout 0.01s 5280KB
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https://ideone.com/Vw9X0T
language:
C++ (gcc 8.3)
created:
40 minutes ago
visibility:
public

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