Create greedy-knapsack_deblina-talukdar.cpp

Data structures and Algorithms/greedy-knapsack_deblina-talukdar.cpp

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+#include<bits/stdc++.h>
+using namespace std;
+#define ll long long
+#define PI 3.14159265
+#define pb push_back
+#define pf push_front
+#define mp make_pair
+#define fs first
+#define sc second
+const ll mod=1e9+7;
+const ll siz=5*1e5+5;
+bool sortinrev(const pair<float,int> &a, const pair<float,int> &b){ 
+       return (a.first > b.first); 
+}
+int main(){
+	int n,i,W,w[siz],v1[siz];
+	float s=0.0;
+	vector<pair<float,int>>v;
+	//getting the number of items in knapsack
+	cin>>n;
+	for(i=0;i<n;i++){
+		cin>>w[i]>>v1[i];
+		v.pb({(float)((float)v1[i]/(float)w[i]),i});
+	}
+	//getting the total weight
+	cin>>W;
+	//sorting in decreasing order of value/weight
+	sort(v.begin(),v.end(),sortinrev);
+	for(i=0;i<n;i++){
+		if(w[v[i].second]<=W){
+			s+=v1[v[i].second];
+			W-=w[v[i].second];
+		}
+		else{
+			s+=(v[i].first*W);
+			W=0;
+			break;
+		}
+	}
+	//sum of values of all items in the knapsack
+	cout<<s;
+	return 0;
+}