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  1. #include<stdio.h>
  2. #include<vector>
  3. using namespace std;
  4. int min(int a, int b) { if (a == 0)return b; if (a < b)return a; return b; }
  5. int max(int a, int b) { if (a == 0)return b; if (a < b)return b; return a; }
  6. struct xy { int x, y; }G[121212], L[121212];
  7. int S[121212], E[121212];
  8. vector<int>ST;
  9. int main() {
  10. 	int n, i, x, ln;
  11. 	scanf("%d", &n);
  12. 	for (i = 1; i <= n; i++) {
  13. 		scanf("%d", &x);
  14. 		G[x].x = min(G[x].x, i);
  15. 		G[x].y = max(G[x].y, i);
  16. 	}
  17. 	for (i = 1; i <= n; i++) if(G[i].x)S[G[i].x] = i, E[G[i].y] = i;
  18. 	int ans = 0;
  19. 	for (i = 1; i <= n; i++) {
  20. 		if (S[i]) ST.push_back(S[i]);
  21. 		if (E[i]) {
  22. 			if (ST.back() != E[i]) { printf("-1"); return 0; }
  23. 			ans = max(ST.size(), ans);
  24. 			ST.pop_back();
  25. 		}
  26. 	}
  27. 	printf("%d", ans);
  28. 	return 0;
  29. }
Success #stdin #stdout 0s 4368KB
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stdout 
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https://ideone.com/y7eKi7
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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