Created binary_index_tree.cpp

Author: guptanitesh

Data Structures/Fenwick_tree/binary_index_tree.cpp

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+#include<bits/stdc++.h>
+using namespace std;
+typedef pair<int,int>   pii;
+typedef vector< pii>      vii;
+typedef vector<int>     vi;
+typedef vector< vi >    vvi;
+typedef long long int   LL;
+#define pb push_back
+#define mp make_pair
+#define scan(n) scanf("%d",&n)
+#define print(n) printf("%d\n",n)
+#define longscan(n) scanf("%lld",&n)
+#define longprint(n) printf("%lld\n",n)
+#define fast_io ios_base::sync_with_stdio(false);cin.tie(NULL)
+/*void sieve(int n)
+  {
+          for(int i=2;i*i<=100000;i++) for(int j=2*i;j<=100000;j+=i) if(!sie[j]) sie[j]=1;
+          }*/
+int n;
+int bit[10000];
+void update(int x, int val)
+{
+    for(; x <= n; x += x & -x)
+    {
+        bit[x] += val;
+    }
+}
+
+int query(int x)
+{
+    int sum = 0;
+    for(; x > 0; x-= x&-x)
+    {
+        sum+= bit[x];
+    }
+    return sum;
+}
+int main()
+{
+    int q;
+    cin >> n >> q;
+    int a[n+9], quer[q+9];
+    for(int j=1;j<=n;j++)
+    {
+        cin >> a[j];
+        update(j,a[j]);
+    }
+    for(int j=1;j<=q;j++)
+    {
+        cin >> quer[j];
+    }
+    for(int j=1;j<=q;j++)
+    {
+        cout << query(quer[j]) << "\n";
+    }
+    return 0;
+}