Create day005sol02.cpp

Author: Naman2251

Problems/Data-structures/Day-05/sol/Naman2251/day005sol02.cpp

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+Submission Link: https://cses.fi/problemset/result/15799460/
+
+/*
+-> I made a vector which stores pair(pair(arrival, departue), person no.).
+-> I sorted so that person coming first gets room first.
+-> I made a priority queue min-heap(element with lower value have higher priority) and stored element as 
+   pair(departure, room no.)
+-> Now I compared each incoming element with the top one only as it has been emptied first. If a[i].first.first then remove 
+   first element and pushed the incoming element and in ans vector put the room else I would add no. of room and push the element 
+   in pq and in ans vector put the room. Now I printed rm(no. of room) and vector ans(in which room each person stays). 
+*/
+
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+    int n;
+    cin>>n;
+    vector<pair<pair<int,int>,int>>a(n);
+    for(int i=0;i<n;i++) {
+        cin>>a[i].first.first;
+        cin>>a[i].first.second;
+        a[i].second=i;
+    }
+    sort(a.begin(),a.end());
+    priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> pq;
+    int rm=1;
+    pq.push({a[0].first.second,rm});
+    vector <int> ans(n);
+    ans[a[0].second]=1;
+    for(int i=1;i<n;i++) {
+        int d=pq.top().first;
+        int r=pq.top().second;
+        if(a[i].first.first>d) {
+            pq.pop();
+            pq.push({a[i].first.second,r});
+            ans[a[i].second]=r;
+        }  
+        else {
+            rm++;
+            pq.push({a[i].first.second,rm});
+            ans[a[i].second]=rm;
+        }
+    }
+    cout<<rm<<endl;
+    for(int i=0;i<n;i++) cout<<ans[i]<<" ";
+    cout<<endl;
+}