140 lines
3.2 KiB
C++
140 lines
3.2 KiB
C++
/* Problem URL: https://cses.fi/problemset/task/2217 */
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#include <bits/stdc++.h>
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using namespace std;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (size_t i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (size_t i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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const int inf = INT32_MAX >> 1;
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int n, m;
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cin >> n >> m;
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vi adj(n + 2, inf);
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adj[0] = -1;
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adj[n + 1] = n;
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vi nums(n);
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cin >> nums;
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ll rounds = 1;
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rep(i, n) {
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if (adj[nums[i] - 1] == inf) {
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rounds++;
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}
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adj[nums[i]] = i;
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}
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vi prev = adj;
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while (m--) {
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int a, b;
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cin >> a >> b;
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a--, b--;
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swap(adj[nums[a]], adj[nums[b]]);
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swap(nums[a], nums[b]);
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if (adj[nums[a] - 1] > adj[nums[a]] && prev[nums[a] - 1] < prev[nums[a]]) {
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rounds++;
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}
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if (adj[nums[a] - 1] < adj[nums[a]] && prev[nums[a] - 1] > prev[nums[a]]) {
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rounds--;
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}
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if (nums[b] != nums[a] + 1) {
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if (adj[nums[b] - 1] > adj[nums[b]] && prev[nums[b] - 1] < prev[nums[b]]) {
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rounds++;
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}
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if (adj[nums[b] - 1] < adj[nums[b]] && prev[nums[b] - 1] > prev[nums[b]]) {
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rounds--;
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}
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}
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if (adj[nums[a] + 1] < adj[nums[a]] && prev[nums[a] + 1] > prev[nums[a]]) {
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rounds++;
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}
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if (adj[nums[a] + 1] > adj[nums[a]] && prev[nums[a] + 1] < prev[nums[a]]) {
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rounds--;
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}
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if (nums[b] != nums[a] - 1) {
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if (adj[nums[b] + 1] < adj[nums[b]] && prev[nums[b] + 1] > prev[nums[b]]) {
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rounds++;
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}
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if (adj[nums[b] + 1] > adj[nums[b]] && prev[nums[b] + 1] < prev[nums[b]]) {
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rounds--;
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}
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}
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cout << rounds << '\n';
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swap(prev[nums[a]], prev[nums[b]]);
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}
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}
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