Submission #56029

#TimeUsernameProblemLanguageResultExecution timeMemory
56029PeppaPigThree Friends (BOI14_friends)C++14
0 / 100
194 ms71012 KiB
#include <bits/stdc++.h> #define pll pair<long long, long long> #define x first #define y second using namespace std; const int N = 2e6 + 5; pll add(pll a, pll b) { return pll(a.x + b.x, a.y + b.y); } pll sub(pll a, pll b) { return pll(a.x - b.x, a.y - b.y); } pll mul(pll a, pll b) { return pll(a.x * b.x, a.y * b.y); } pll id[N]; int n, cnt, pos; pll dp[N]; string str; int main() { id[1] = {101LL, 103LL}; for(int i = 2;i < N;i++) id[i] = mul(id[i - 1], id[1]); scanf("%d", &n); if(!(n & 1)) return !printf("NOT POSSIBLE"); cin >> str; dp[0] = {str[0], str[0]}; for(int i = 1;i < n;i++) dp[i] = add(mul(pll(str[i], str[i]), id[i]), dp[i - 1]); if(mul(sub(dp[n >> 1], dp[0]), id[n >> 1]) == sub(dp[n - 1], dp[n >> 1])) cnt++, pos = 0; if(mul(dp[(n >> 1) - 1], id[n >> 1]) == sub(dp[n - 2], dp[(n >> 1) - 1])) cnt++, pos = n - 1; for(int i = 1;i < n >> 1;i++) if(sub(dp[n - 1], dp[n >> 1]) == mul(add(sub(dp[n >> 1], dp[i]), mul(dp[i - 1], id[1])), id[n >> 1])) cnt++, pos = i; if(mul(dp[(n >> 1) - 1], id[(n >> 1) + 1]) == sub(dp[n - 1], dp[n >> 1])) cnt++, pos = n >> 1; for(int i = (n >> 1) + 1;i < n;i++) if(mul(dp[(n >> 1) - 1], id[(n >> 1) + 1]) == add(mul(sub(dp[i - 1], dp[(n >> 1) - 1]), id[1]), sub(dp[n - 1], dp[i]))) cnt++, pos = i; if(!cnt) printf("NOT POSSIBLE"); else if(cnt == 1) { if(!pos) cout << str.substr(1, n >> 1) << endl; else if(pos == n - 1) cout << str.substr(0, n >> 1) << endl; else cout << (str.substr(0, pos) + str.substr(pos + 1, n - pos - 1)).substr(0, n >> 1) << endl; } else printf("NOT UNIQUE"); return 0; }

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:24:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
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