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| #include <bits/stdc++.h> |
| using namespace std; |
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| #define ll long long |
| #define ull unsigned long long |
| #define dd double |
| #define ld long double |
| #define sl(n) scanf("%lld", &n) |
| #define si(n) scanf("%d", &n) |
| #define sd(n) scanf("%lf", &n) |
| #define pll pair <ll, ll> |
| #define pii pair <int, int> |
| #define mp make_pair |
| #define pb push_back |
| #define all(v) v.begin(), v.end() |
| #define inf (1LL << 62) |
| #define loop(i, start, stop, inc) for(ll i = start; i <= stop; i += inc) |
| #define for1(i, stop) for(ll i = 1; i <= stop; ++i) |
| #define for0(i, stop) for(ll i = 0; i < stop; ++i) |
| #define rep1(i, start) for(ll i = start; i >= 1; --i) |
| #define rep0(i, start) for(ll i = (start-1); i >= 0; --i) |
| #define ms(n, i) memset(n, i, sizeof(n)) |
| #define casep(n) printf("Case %lld:", ++n) |
| #define pn printf("\n") |
| #define pf printf |
| #define EL '\n' |
| #define fastio std::ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); |
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| typedef vector <int> vi; |
| const double PI = 2.0 * acos(0.0); |
| using cd = complex<double>; |
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| void fft(vector<cd> & a, bool invert = 0) |
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| { |
| int n = a.size(); |
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| for (int i = 1, j = 0; i < n; i++) { |
| int bit = n >> 1; |
| for (; j & bit; bit >>= 1) |
| j ^= bit; |
| j ^= bit; |
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| if (i < j) |
| swap(a[i], a[j]); |
| } |
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| for (int len = 2; len <= n; len <<= 1) { |
| double ang = 2 * PI / len * (invert ? -1 : 1); |
| cd wlen(cos(ang), sin(ang)); |
| for (int i = 0; i < n; i += len) { |
| cd w(1); |
| for (int j = 0; j < len / 2; j++) { |
| cd u = a[i+j], v = a[i+j+len/2] * w; |
| a[i+j] = u + v; |
| a[i+j+len/2] = u - v; |
| w *= wlen; |
| } |
| } |
| } |
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| if (invert) { |
| for (cd & x : a) |
| x /= n; |
| } |
| } |
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| void ifft(vector <cd> & p) |
| |
| { |
| fft(p, 1); |
| } |
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| vi multiply(vi const& a, vi const& b) |
| { |
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| vector<cd> fa(a.begin(), a.end()), fb(b.begin(), b.end()); |
| int n = 1; |
| while (n < a.size() + b.size()) |
| n <<= 1; |
| fa.resize(n); |
| fb.resize(n); |
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| fft(fa); |
| fft(fb); |
| for (int i = 0; i < n; i++) |
| fa[i] *= fb[i]; |
| ifft(fa); |
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| vi result(n); |
| for (int i = 0; i < n; i++) |
| result[i] = round(fa[i].real()); |
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| return result; |
| } |
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| const ll sz = 5e5 + 10, offset = 5e5; |
| char s[sz], r[sz]; |
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| vi num1[4], num2[4], res[4]; |
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| int main() |
| { |
| scanf("%s %s", s, r); |
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| ll len1 = strlen(s), len2 = strlen(r); |
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| for0(i, 4) |
| num1[i].resize(len1+1,0), num2[i].resize(len2+1+offset,0); |
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| for(ll i = 0; s[i] != '\0'; i++) { |
| if(s[i] == 'A') |
| num1[0][i]++; |
| else if(s[i] == 'C') |
| num1[1][i]++; |
| else if(s[i] == 'T') |
| num1[2][i]++; |
| else |
| num1[3][i]++; |
| } |
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| for(ll i = 0; r[i] != '\0'; i++) { |
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| if(r[i] == 'A') |
| num2[0][-i + offset]++; |
| else if(r[i] == 'C') |
| num2[1][-i + offset]++; |
| else if(r[i] == 'T') |
| num2[2][-i + offset]++; |
| else |
| num2[3][-i + offset]++; |
| } |
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| for0(i, 4) res[i] = multiply(num1[i], num2[i]); |
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| ll ans = inf; |
| for(ll i = 0; i <= len1 - len2; i++) { |
| ll match = 0; |
| for0(j, 4) match += res[j][i+offset]; |
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| ans = min(ans, len2-match); |
| } |
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| cout << ans << EL; |
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| return 0; |
| } |
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