basic prefix sum

prefix_sum/prefix_sum.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+
+/*
+return a vector of prefix sum of the inputed vector
+
+Parameter:
+- vector long long
+
+Return:
+- vector long long of size inputed vector + 1(cause first element will be 0)
+*/
+vector<long long> prefix_sum(vector<long long> v)
+{
+    // initializing prefix sum vector
+    long long n = v.size();
+    vector<long long> psum(n + 1, 0);
+    for (long long i = 1; i <= n; i++)
+    {
+        psum[i] = psum[i - 1] + v[i - 1];
+    }
+    return psum;
+}
+
+int main()
+{
+    vector<long long> v = {4, 3, 2, 5};
+    for (long long x : prefix_sum(v))
+        cout << x << ' ';
+    return 0;
+}