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  1. #include <bits/stdc++.h>
  2. typedef long long ll;
  3. using namespace std;
  4. const int N = 100000 + 5;
  5. char st[N];
  6. bool other[N];
  7. int n, m, res, cnt, ti;
  8. char c;
  9. int O(int i) { return n-i-1; }
  10. int main() {
  11. 	int T;
  12. 	scanf("%d", &T);
  13. 	while(T--) {
  14. 		scanf("%d%d%s", &n,&m,st);
  15. 		for(int i=0; i<n; ++i)
  16. 			other[i] = true;
  17. 		cnt = 0;
  18. 		for(int i=0; i<=O(i); ++i)
  19. 			if(st[i] != st[O(i)]) {
  20. 				other[i] = other[O(i)] = false;
  21. 				++cnt;
  22. 			}
  23. 		res = 0;
  24. 		for(int j=0; j<m; ++j) {
  25. 			scanf("%d %c", &ti, &c);
  26. 			--ti;
  27. 			st[ti] = c;
  28. 			if(other[ti] == true) {
  29. 				if(st[ti] != st[O(ti)]) {
  30. 					other[ti] = other[O(ti)] = false;
  31. 					++cnt;
  32. 				}
  33. 			} else if(other[ti] == false) {
  34. 				if(st[ti] == st[O(ti)]) {
  35. 					other[ti] = other[O(ti)] = true;
  36. 					--cnt;
  37. 				}
  38. 			}
  39. 			if(cnt == 0) ++res;
  40. 		}
  41. 		printf("%d\n", res);
  42. 	}
  43. 	return 0;
  44. }
Success #stdin #stdout 0s 4484KB
comments (?)
stdin
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1
10 7
abcdefdcba
5 x
6 x
4 d
2 d
3 y
8 y
9 d
stdout
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3
https://ideone.com/C6X94O
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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