fix: dynamic array in coin_change

Author: realstealthninja

dynamic_programming/coin_change.cpp

@@ -1,11 +1,13 @@
 #include <climits>
 #include <iostream>
+#include <vector>
 using namespace std;
 
 // Function to find the Minimum number of coins required to get Sum S
 int findMinCoins(int arr[], int n, int N) {
     // dp[i] = no of coins required to get a total of i
-    int dp[N + 1];
+    std::vector<int> dp;
+    dp.reserve(N + 1);
 
     // 0 coins are needed for 0 sum