Submission #373504

#TimeUsernameProblemLanguageResultExecution timeMemory
373504qpwoeirutXOR Sum (info1cup17_xorsum)C++17
0 / 100
454 ms131076 KiB
//xorsum.cpp created at 03/04/21 10:30:22 #include <bits/stdc++.h> using namespace std; const int MN = 1000006; const int LG = 24; int N; int A[MN]; int psum[(1 << (LG + 1)) + 1]; int main() { cin.tie(0)->sync_with_stdio(0); cin >> N; for (int i=0; i<N; ++i) { cin >> A[i]; } int ans = 0; for (int i=0; i<LG; ++i) { fill(psum, psum + (1 << (i+2)) + 1, 0); for (int j=0; j<N; ++j) { ++psum[(A[j] & ((1 << (i + 1)) - 1)) + 1]; // add 1 for easy indexing stuff } for (int j=1; j<=(1 << (i+2)); ++j) { psum[j] += psum[j - 1]; } // range [2^i, 2^(i+1)) and [2^(i+1) + 2^i, 2^(i+2)) int ct = 0; for (int j=0; j<N; ++j) { const int val = A[j] & ((1 << (i + 1)) - 1); const int lo1 = (1 << i) - val; ct += psum[(1 << (i + 1)) - val] - psum[lo1 < 0 ? 0 : lo1]; const int lo2 = min(1 << (i+2), (1 << (i + 1)) + lo1); const int hi2 = min(1 << (i+2), (1 << (i + 2)) - val); ct += psum[hi2] - psum[lo2]; ct += ((A[j] << 1) >> i) & 1; } assert((ct & 1) == 0); ct = (ct >> 1) & 1; ans += ct << i; } for (int i=LG; i<=30; ++i) { } cout << ans << '\n'; } /* 4 3 9 6 6 00110 1 1 01100 1 2 01001 1 3 01001 1 4 10010 2 2 01111 2 3 01111 2 4 01100 3 3 01100 3 4 01100 4 4 */
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