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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define int long long
  4. #define fi first
  5. #define se second
  6. #define siz(x) (int)(x.size())
  7. #define all(x) x.begin(), x.end()
  8. #define debug_arr(x,len) for(int _=1; _<=len; _++) cout<<x[_]<<" "; cout<<'\n';
  9. #define debug(x) cout<<'\n'<<#x<<": "<<x<<'\n';
  10. const int maxN=2e5+5;
  11.  
  12. int n, m, a[maxN], dp[maxN];
  13. void solve()
  14. {
  15.  
  16. }
  17.  
  18. int32_t main()
  19. {
  20.     ios_base::sync_with_stdio(0); cin.tie(0);
  21.     int test=1;
  22.     cin>>test;
  23.     while(test--)
  24.     {
  25.         cin>>n>>m;
  26.         map<int,int>mp;
  27.         for(int i=1; i<=n+1; i+=1) dp[i]=0;
  28.         for(int i=1; i<=m; i+=1) cin>>a[i], mp[min(n,a[i])]++;
  29.         dp[n+1]=0;
  30.         for(int i=n; i>=1; i-=1)
  31.         {
  32.             dp[i]=dp[i+1]+mp[i];
  33.         }
  34.         // debug_arr(dp, n);
  35.         int ans=0;
  36.         for(int i=1; i<n; i+=1)
  37.         {
  38.             ans=(long long)(ans+1ll*dp[i]*dp[n-i]);
  39.         }
  40.         for(int i=1; i<n; i+=1)
  41.         {
  42.             ans-=dp[max(i,n-i)];
  43.         }
  44.         cout<<ans<<'\n';
  45.         solve();
  46.     }
  47. }
  48.  
  49. // dp[i] la so mau co >= i hop son
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/qi4M42
language:
C++14 (gcc 8.3)
created:
283 days ago
visibility:
public

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