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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4. #include <memory.h>
  5. #include <assert.h>
  6.  
  7. using namespace std;
  8.  
  9. int N, M, graph[1001][1001];
  10. int main() {
  11. 	scanf("%d", &N);
  12. 	scanf("%d", &M);
  13. 	while (M--) {
  14. 		int u, v;
  15. 		scanf("%d %d", &u, &v);
  16. 		graph[u][v] = graph[v][u] = 1;
  17. 	}
  18. 	long long diffColor = 0;
  19. 	for (int i = 1; i <= N; i++) {
  20. 		int blackCount = 0, redCount = 0;
  21. 		for (int j = 1; j <= N; j++) {
  22. 			if (i != j) {
  23. 				blackCount += !graph[i][j];
  24. 				redCount += graph[i][j];
  25. 			}
  26. 		}
  27. 		diffColor += blackCount * redCount;
  28. 	}
  29. 	assert(diffColor % 2 == 0);
  30. 	long long sameColor = (long long)N * (N - 1) * (N - 2) / 6 - diffColor / 2;
  31. 	printf("%lld\n", sameColor);
  32. 	return 0;
  33. }
  34.  
Success #stdin #stdout 0s 19144KB
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https://ideone.com/2cnYjr
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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