first 7 Introductory problems

CSES - CSES Problem Set/Increasing_Array.cpp

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+//  Increasing Array
+
+#include<bits/stdc++.h>
+
+using namespace std;
+typedef long long ll;
+
+int main() {
+    int n;
+    cin >> n;
+    vector<ll> array(n);
+    for (auto &e : array) cin >> e;
+    ll count = 0;
+    for (int i = 1; i < n; i++) {
+        if (array[i] < array[i-1]) {
+            count += array[i-1] - array[i];
+            array[i] = array[i-1];
+        }
+    }
+    cout << count << endl;
+    return 0;
+}