Create solution.cpp

Author: aishsingh

LemonadeChange/solution.cpp

@@ -0,0 +1,79 @@
+class Solution {
+public:
+    bool lemonadeChange(vector<int>& bills) 
+    {
+        unordered_map<int, int> billsCollectedCount;
+
+        const int lemonadePrice = 5;
+
+        for (const auto& billGiven : bills)
+        {
+            // calc change
+            int changeNeeded = billGiven - lemonadePrice;
+
+            switch (changeNeeded)
+            {
+                case 15:
+                {
+                    // check if a $5 and $10 bill is available
+                    if (billsCollectedCount[10] >= 1 &&
+                        billsCollectedCount[5] >= 1 )
+                    {
+                        billsCollectedCount[10]--;
+                        billsCollectedCount[5]--;
+                        changeNeeded -= 15;
+                    }
+                    // check if a 3 $5 bills are available
+                    else if (billsCollectedCount[5] >= 3)
+                    {
+                        billsCollectedCount[5] -= 3;
+                        changeNeeded -= 5*3;
+                    }
+
+                    break;
+                }
+
+                case 10:
+                {
+                    // check if a $10 bill is available
+                    if (billsCollectedCount[10] >= 1)
+                    {
+                        billsCollectedCount[10]--;
+                        changeNeeded -= 10;
+                    }
+                    // check if 2 $5 bills are available
+                    else if (billsCollectedCount[5] >= 2)
+                    {
+                        billsCollectedCount[5] -= 2;
+                        changeNeeded -= 5*2;
+                    }
+
+                    break;
+                }
+
+                case 5:
+                {
+                    if (billsCollectedCount[5] >= 1)
+                    {
+                        billsCollectedCount[5]--;
+                        changeNeeded -= 5;
+                    }
+                    break;
+                }
+
+            }
+
+            // Check if change was found
+            if (changeNeeded > 0)
+            {
+                return false;
+            }
+
+            // collect bill
+            billsCollectedCount[billGiven]++;
+        }
+
+        // if we readched here then the correct amount of bills needed for all of the customers change was found
+        return true;
+    }
+};