Create lasers-and-mirrors.cpp

Author: AymanSalah96

USACO/lasers-and-mirrors.cpp

@@ -0,0 +1,144 @@
+#include <cstring>
+#include <map>
+#include <deque>
+#include <queue>
+#include <stack>
+#include <sstream>
+#include <numeric>
+#include <iostream>
+#include <iomanip>
+#include <cstdio>
+#include <cmath>
+#include <fstream>
+#include <string>
+#include <cstdlib>
+#include <ctime>
+#include <functional>
+#include <algorithm>
+#include <vector>
+#include <set>
+#include <complex>
+#include <list>
+#include <climits>
+#include <cctype>
+#include <bitset>
+using namespace std;
+
+#define PI 3.14159265359
+#define all(v) v.begin(),v.end()
+#define sortva(v) sort(all(v))
+#define sortvd(v) sort(v.rbegin(),v.rend())
+#define sortaa(a,n) sort(a,a+n)
+#define sortad(a,n) sort(a,a+n),reverse(a,a+n)
+#define sfi1(v) scanf("%d",&v)
+#define sfi2(v1,v2) scanf("%d %d",&v1,&v2)
+#define sfi3(v1,v2,v3) scanf("%d %d %d",&v1,&v2,&v3)
+#define sfll1(v) scanf("%I64d",&v);
+#define sfll2(v1,v2) scanf("%I64d %I64d",&v1,&v2)
+#define sfll3(v1,v2,v3) scanf("%I64d %I64d %I64d",&v1,&v2,&v3)
+#define sfstr(v) scanf("%s", v);
+#define sz(v) (int)v.size()
+#define ndl puts("")
+#define flush fflush(stdout)
+#define SS stringstream
+typedef long long ll;
+typedef unsigned long long ull;
+typedef long double ld;
+
+int dx[] = { 0, 0, 1, -1, 1, -1, 1, -1 };
+int dy[] = { 1, -1, 0, 0, -1, 1, 1, -1 };
+
+ll gcd(ll a, ll b) { return !b ? a : gcd(b, a % b); }
+ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; }
+
+void PLAY() {
+//#ifndef ONLINE_JUDGE
+freopen("lasers.in", "r", stdin);
+freopen("lasers.out", "w", stdout);
+//#endif
+
+cout << fixed << setprecision(10);
+ios::sync_with_stdio(0);
+cin.tie(0);
+cout.tie(0);
+}
+
+const int MAX = 1e6;
+
+pair<pair<int, int>, int> arr[MAX];
+pair<pair<int, int>, int> arr1[MAX];
+vector<pair<int, int>> adj[MAX];
+bool vis[MAX];
+
+int main() {
+PLAY();
+
+int n;
+cin >> n;
+n += 2;
+for (int i = 0, idx = 0; i < n; i++, idx += 2) {
+cin >> arr[i].first.first >> arr[i].first.second;
+arr[i].second = idx;
+arr1[i] = { { arr[i].first.second, arr[i].first.first }, idx + 1 };
+adj[idx].push_back({ idx + 1, 1 });
+adj[idx + 1].push_back({ idx, 1 });
+}
+int from1 = 0, from2 = 1;
+int to1 = 2, to2 = 3;
+
+sort(arr, arr + n);
+map<int, int> prev;
+
+for (int i = 0; i < n; i++) {
+if (prev.find(arr[i].first.first) == prev.end())
+prev[arr[i].first.first] = arr[i].second;
+else {
+int p = prev[arr[i].first.first];
+adj[p].push_back({ arr[i].second, 0 });
+adj[arr[i].second].push_back({ p, 0 });
+prev[arr[i].first.first] = arr[i].second;
+}
+}
+
+sort(arr1, arr1 + n);
+prev.clear();
+
+for (int i = 0; i < n; i++) {
+if (prev.find(arr1[i].first.first) == prev.end())
+prev[arr1[i].first.first] = arr1[i].second;
+else {
+int p = prev[arr1[i].first.first];
+adj[p].push_back({ arr1[i].second, 0 });
+adj[arr1[i].second].push_back({ p, 0 });
+prev[arr1[i].first.first] = arr1[i].second;
+}
+}
+
+deque<pair<int, int>> qu;
+qu.push_back({ from1, 0 });
+qu.push_back({ from2, 0 });
+
+while (sz(qu)) {
+int cur_node = qu.front().first;
+int cur_cost = qu.front().second;
+if (cur_node == to1 || cur_node == to2) {
+cout << cur_cost << endl;
+return 0;
+}
+qu.pop_front();
+if (vis[cur_node]) continue;
+vis[cur_node] = true;
+for (int i = 0; i < sz(adj[cur_node]); i++) {
+int to_node = adj[cur_node][i].first;
+int to_cost = adj[cur_node][i].second;
+if (!vis[to_node]) {
+if (to_cost) qu.push_back({ to_node, cur_cost + 1 });
+else qu.push_front({ to_node, cur_cost });
+}
+}
+}
+
+cout << -1 << endl;
+
+return 0;
+}