add a solution for 860

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/firstthousand/_860.java

@@ -54,4 +54,37 @@ public boolean lemonadeChange(int[] bills) {
             return true;
         }
     }
+
+    public static class Solution2 {
+        /**
+         * My original solution on 8/14/2024.
+         * You only need to keep track of the number of $5 and $10 bills at hand.
+         */
+
+        public boolean lemonadeChange(int[] bills) {
+            int[] changes = new int[2];//5 and 10
+            for (int bill : bills) {
+                if (bill == 5) {
+                    changes[0]++;
+                } else if (bill == 10) {
+                    if (changes[0] <= 0) {
+                        return false;
+                    } else {
+                        changes[0]--;
+                    }
+                    changes[1]++;
+                } else if (bill == 20) {
+                    if (changes[1] > 0 && changes[0] > 0) {
+                        changes[1]--;
+                        changes[0]--;
+                    } else if (changes[0] > 2) {
+                        changes[0] -= 3;
+                    } else {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+    }
 }

src/test/java/com/fishercoder/firstthousand/_860Test.java

@@ -8,41 +8,41 @@
 
 public class _860Test {
 
-  private _860.Solution1 test;
-  private static int[] bills;
+    private _860.Solution1 test;
+    private static int[] bills;
 
-  @BeforeEach
+    @BeforeEach
     public void setUp() {
-    test = new _860.Solution1();
-  }
-
-  @Test
-  public void test1() {
-    bills = new int[] {5, 5, 5, 10, 20};
-    assertEquals(true, test.lemonadeChange(bills));
-  }
-
-  @Test
-  public void test2() {
-    bills = new int[] {5, 5, 10};
-    assertEquals(true, test.lemonadeChange(bills));
-  }
-
-  @Test
-  public void test3() {
-    bills = new int[] {10, 10};
-    assertEquals(false, test.lemonadeChange(bills));
-  }
-
-  @Test
-  public void test4() {
-    bills = new int[] {5, 5, 10, 10, 20};
-    assertEquals(false, test.lemonadeChange(bills));
-  }
-
-  @Test
-  public void test5() {
-    bills = new int[] {5, 5, 5, 20, 5, 5, 5, 10, 20, 5, 10, 20, 5, 20, 5, 10, 5, 5, 5, 5};
-    assertEquals(false, test.lemonadeChange(bills));
-  }
+        test = new _860.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        bills = new int[]{5, 5, 5, 10, 20};
+        assertEquals(true, test.lemonadeChange(bills));
+    }
+
+    @Test
+    public void test2() {
+        bills = new int[]{5, 5, 10};
+        assertEquals(true, test.lemonadeChange(bills));
+    }
+
+    @Test
+    public void test3() {
+        bills = new int[]{10, 10};
+        assertEquals(false, test.lemonadeChange(bills));
+    }
+
+    @Test
+    public void test4() {
+        bills = new int[]{5, 5, 10, 10, 20};
+        assertEquals(false, test.lemonadeChange(bills));
+    }
+
+    @Test
+    public void test5() {
+        bills = new int[]{5, 5, 5, 20, 5, 5, 5, 10, 20, 5, 10, 20, 5, 20, 5, 10, 5, 5, 5, 5};
+        assertEquals(false, test.lemonadeChange(bills));
+    }
 }