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  1. //ZJ. Cặp số gần nhất
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5. #define ll long long
  6. #define For(i, a, b) for(int i = a; i <= b; ++i)
  7. #define endl '\n'
  8.  
  9. const int maxn = 3e5 + 5;
  10. const int INF = 1e9;
  11.  
  12. int n, q, a[maxn], pre[maxn], bit[maxn], ans[maxn];
  13. vector<pair<int, int>> qr[maxn];
  14. unordered_map<int, int> last;
  15.  
  16. void update(int i, int val)
  17. {
  18.     for(; i <= n; i += i & -i)
  19.         bit[i] = min(bit[i], val);
  20. }
  21.  
  22. int get(int i)
  23. {
  24.     int res = INF;
  25.     for(; i > 0; i -= i & -i)
  26.         res = min(res, bit[i]);
  27.     return res;
  28. }
  29.  
  30. signed main()
  31. {
  32.     ios_base::sync_with_stdio(false);
  33.     cin.tie(NULL); cout.tie(NULL);
  34.  
  35.     cin >> n >> q;
  36.  
  37.     For(i, 1, n) cin >> a[i];
  38.  
  39.     For(i, 1, n)
  40.     {
  41.         if(last.count(a[i])) pre[i] = last[a[i]];
  42.         else pre[i] = 0;
  43.         last[a[i]] = i;
  44.     }
  45.  
  46.     For(i, 1, q)
  47.     {
  48.         int l, r;
  49.         cin >> l >> r;
  50.         qr[r].push_back({l, i});
  51.     }
  52.  
  53.     For(i, 1, n) bit[i] = INF;
  54.  
  55.     For(i, 1, n)
  56.     {
  57.         if(pre[i])
  58.         {
  59.             int pos = n - pre[i] + 1;
  60.             update(pos, i - pre[i]);
  61.         }
  62.  
  63.         for(auto [l, id] : qr[i])
  64.         {
  65.             int pos = n - l + 1;
  66.             ans[id] = get(pos);
  67.         }
  68.     }
  69.  
  70.     For(i, 1, q)
  71.     {
  72.         if(ans[i] == INF) cout << -1 << endl;
  73.         else cout << ans[i] << endl;
  74.     }
  75. }
  76.  
Success #stdin #stdout 0.01s 12388KB
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https://ideone.com/haQwjA
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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