Aprendi Fenwick Tree! (Binary Indexed Tree)

Problems/NepsAcademy/neps_43.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+vector<int> bit, vetor_100pct_original;
+
+void update_bit(int pos, int x){
+	int pracsum = -vetor_100pct_original[pos-1];
+	vetor_100pct_original[pos-1] = x;
+	for(; pos <= bit.size(); pos += (pos&-pos)){
+		bit[pos] += pracsum + x;
+	}
+}
+
+int sumrange_bit(int pos){
+	int answ = 0;
+	for(; pos > 0; pos -= (pos&-pos)){
+		answ += bit[pos];
+	}
+	return answ;
+}
+
+int main(){
+	ios::sync_with_stdio(false);
+
+	int n,q, x, t,k,p;
+	cin >> n >> q;
+
+	bit.assign(n+1,0);
+	vetor_100pct_original.assign(n,0);
+	for(int i = 1; i <= n; i++){
+		cin >> x;
+		bit[i] += x;
+		vetor_100pct_original[i-1] = x;
+		for(int j = i+(i&-i); j <= n; j += (j&-j)){
+			bit[j] += x;
+		}
+	}
+
+	while(q--){
+		cin >> t >> k;
+		if(t == 0){
+			cin >> p;
+			update_bit(k, p);
+		}else{
+			cout << sumrange_bit(k) << '\n';
+		}
+	}
+
+	return 0;
+}