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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#235252 | #7613. Inverse Problem | dykw | WA | 18088ms | 127376kb | C++20 | 3.3kb | 2023-11-02 16:27:42 | 2023-11-02 16:27:44 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
constexpr int maxn = 125;
constexpr int mod = (int) 1e9 + 7;
bitset<mod> f;
int t;
int r[10];
vector<int> rid;
int w[126][126], iw[126][126], inv[126];
vector<pair<int, int>> g[126], h[126];
void dfs(int x, int used, int res, const int &n) {
f[res] = 1;
for (int i = x; i <= min(n - 2, 6); ++i) {
if (used + i > n - 2) {
break;
}
dfs(i, used + i, 1LL * res * w[n - 2][i] % mod, n);
}
}
void dfs_b(int x, int used, int res, const int &n) {
for (int i : rid) {
if (f[1LL * r[i] * inv[n] % mod * inv[n - 1] % mod * res % mod]) {
g[used].emplace_back(i, res);
}
}
for (int i = x; i <= n - 2; ++i) {
if (used + i > n - 2) {
break;
}
dfs_b(i, used + i, 1LL * res * iw[n - 2][i] % mod, n);
}
}
int ans_n[10];
vector<int> tmp;
vector<int> siz[10];
void dfs_chk(int x, int used, int res, const int &n) {
for (auto [i, v] : g[n - 2 - used]) {
if (1LL * res * n % mod * (n - 1) % mod == 1LL * r[i] * v % mod) {
ans_n[i] = n;
siz[i] = tmp;
h[n - 2 - used].emplace_back(i, v);
}
}
for (int i = x; i <= min(6, n - 2); ++i) {
if (used + i > n - 2) {
break;
}
tmp.push_back(i);
dfs_chk(i, used + i, 1LL * res * w[n - 2][i] % mod, n);
tmp.pop_back();
}
}
void dfs_rem(int x, int used, int res, const int &n) {
for (auto [i, v] : h[used]) {
if (res == v) {
for (int u : tmp) {
siz[i].push_back(u);
}
}
}
for (int i = x; i <= n - 2; ++i) {
if (used + i > n - 2) {
break;
}
tmp.push_back(i);
dfs_rem(i, used + i, 1LL * res * iw[n - 2][i] % mod, n);
tmp.pop_back();
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> t;
for (int i = 0; i < t; ++i) {
cin >> r[i];
if (r[i] == 1) {
ans_n[i] = 1;
} else if (r[i] == 2) {
ans_n[i] = 2;
} else {
rid.push_back(i);
}
}
inv[1] = 1;
for (int i = 2; i <= 125; ++i) {
inv[i] = 1LL * (mod - mod / i) * inv[mod % i] % mod;
}
for (int i = 1; i <= 125; ++i) {
w[i][0] = iw[i][0] = 1;
for (int j = 1; j <= i; ++j) {
w[i][j] = 1LL * w[i][j - 1] * (i - j + 1) % mod;
iw[i][j] = 1LL * iw[i][j - 1] * inv[i - j + 1] % mod;
}
}
auto clk = clock();
for (int n = 3; n <= maxn; ++n) {
if (rid.empty()) {
break;
}
f.reset();
for (int i = 0; i <= n; ++i) {
g[i].clear();
h[i].clear();
}
dfs(1, 0, 1, n);
dfs_b(7, 0, 1, n);
dfs_chk(1, 0, 1, n);
assert(tmp.empty());
dfs_rem(7, 0, 1, n);
for (int i = 0; i < t; ++i) {
if (ans_n[i] != 0 && find(rid.begin(), rid.end(), i) != rid.end()) {
rid.erase(find(rid.begin(), rid.end(), i));
}
}
}
cerr << "Elp: " << clock() - clk << '\n';
for (int i = 0; i < t; ++i) {
cout << ans_n[i] << '\n';
if (ans_n[i] == 2) {
cout << "1 2" << '\n';
} else if (ans_n[i] != 1) {
cout << "1 2" << '\n';
int lst = 2;
for (int k : siz[i]) {
int now = lst;
while (k--) {
++now;
cout << lst << ' ' << now << '\n';
}
lst = now;
}
}
}
}
Details
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Test #1:
score: 100
Accepted
time: 73ms
memory: 125692kb
input:
4 2 360 1 509949433
output:
2 1 2 5 1 2 2 3 3 4 3 5 1 10 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10
result:
ok OK (4 test cases)
Test #2:
score: -100
Wrong Answer
time: 18088ms
memory: 127376kb
input:
9 185396120 468170792 837583517 696626231 338497514 762842660 800028852 928391161 733524004
output:
14 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 10 12 12 13 12 14 122 1 2 2 3 3 4 4 5 5 6 6 7 7 8 7 9 9 10 9 11 11 12 11 13 13 14 13 15 13 16 16 17 16 18 16 19 19 20 19 21 19 22 22 23 22 24 22 25 22 26 26 27 26 28 26 29 26 30 30 31 30 32 30 33 30 34 30 35 35 36 35 37 35 38 35 39 35 40 35 41 35 42 42 4...
result:
wrong answer Integer 123 violates the range [1, 122]