Range Sum Problem Solved Using Prefix Sum

Author: MohammadFahad1

input.txt

@@ -0,0 +1,5 @@
+4 3
+5 5 2 3
+1 3
+2 3
+1 4

output.txt

@@ -0,0 +1,3 @@
+12
+7
+15

range_sum_query.cpp

@@ -0,0 +1,31 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+    long long int n, q;
+    cin >> n >> q;
+    long long int a[n];
+    long long int pre[n] = {0};
+    for (long long int i = 0; i < n; i++)
+    {
+        cin >> a[i];
+        if (i != 0)
+            pre[i] = a[i] + pre[i - 1];
+        else
+            pre[i] = a[i];
+    }
+
+    while (q--)
+    {
+        long long int l, r;
+        cin >> l >> r;
+        l--;
+        r--;
+        long long int sum = 0;
+        l == 0 ? sum = pre[r] : sum = pre[r] - pre[l - 1];
+        cout << sum << endl;
+    }
+
+    return 0;
+}

range_sum_query.exe

@@ -1 +1,4 @@
-int
+ong int i = 0; i < n; i++)
+    // {
+    //     cout << pre[i] << endl;
+    // }