Fractional knapsack

Author: coderick14

frac_knapsack.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define pll pair<ll,ll>
+using namespace std;
+
+bool comp(pll a, pll b) {
+    float ratio1 = float(a.first)/float(a.second);
+    float ratio2 = float(b.first)/float(b.second);
+    return ratio1 > ratio2;
+}
+
+int main() {
+    ll i,value,weight,n,w;
+    cin>>n>>w;
+    vector<pll > ratio;
+    for(i=0;i<n;i++) {
+        cin>>value>>weight;
+        ratio.push_back(make_pair(value,weight));
+    }
+    sort(ratio.begin(), ratio.end(), comp);
+    float res = 0.0;
+    i = 0;
+    while(i<n && w-ratio[i].second >= 0) {
+        res += ratio[i].first;
+        w -= ratio[i].second;
+        i++;
+    }
+    if(i<n) {
+        res += (float(ratio[i].first)/float(ratio[i].second))*w;
+    }
+    cout<<res<<endl;
+    return 0;
+}