add 3186

Author: fishercoder1534

Diff for: paginated_contents/algorithms/4th_thousand/README.md

@@ -1,5 +1,6 @@
 | #    | Title                                                                                                                                   | Solutions                                                                                                          | Video                                                                         | Difficulty | Tag                                                                  
 |------|-----------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------|----------------------------------------------------------------------
+| 3186 | [Maximum Total Damage With Spell Casting](https://leetcode.com/problems/maximum-total-damage-with-spell-casting/)                       | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_3186.java) |                                                                               | Medium     | DP
 | 3185 | [Count Pairs That Form a Complete Day II](https://leetcode.com/problems/count-pairs-that-form-a-complete-day-ii/)                       | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_3185.java) |                                                                               | Medium     |
 | 3184 | [Count Pairs That Form a Complete Day I](https://leetcode.com/problems/count-pairs-that-form-a-complete-day-i/)                         | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_3184.java) |                                                                               | Easy       |
 | 3178 | [Find the Child Who Has the Ball After K Seconds](https://leetcode.com/problems/find-the-child-who-has-the-ball-after-k-seconds/)       | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/_3178.java) |                                                                               | Easy       |

Diff for: src/main/java/com/fishercoder/solutions/_3186.java

@@ -0,0 +1,36 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.TreeMap;
+
+public class _3186 {
+    public static class Solution1 {
+        public long maximumTotalDamage(int[] power) {
+            TreeMap<Integer, Integer> treeMap = new TreeMap<>();
+            for (int p : power) {
+                treeMap.put(p, treeMap.getOrDefault(p, 0) + 1);
+            }
+            List<Integer> sortedList = new ArrayList<>(treeMap.keySet());
+            long[] dp = new long[sortedList.size()];
+            dp[0] = (long) sortedList.get(0) * treeMap.get(sortedList.get(0));
+            for (int i = 1; i < sortedList.size(); i++) {
+                int currentPower = sortedList.get(i);
+                long currentDamage = (long) currentPower * treeMap.get(currentPower);
+                //from i - 1, all the way to the left of this sorted list, check to find the nearest valid power
+                //using this test case: new int[]{7, 1, 6, 3}, would easily illustrate this idea
+                //dp[i] holds the maximum possible damage for up to sortedList[i]
+                int j = i - 1;
+                while (j >= 0 && sortedList.get(j) >= currentPower - 2) {
+                    j--;
+                }
+                if (j >= 0) {
+                    dp[i] = Math.max(dp[i - 1], currentDamage + dp[j]);
+                } else {
+                    dp[i] = Math.max(dp[i - 1], currentDamage);
+                }
+            }
+            return dp[dp.length - 1];
+        }
+    }
+}

Diff for: src/test/java/com/fishercoder/_3186Test.java

@@ -0,0 +1,32 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._3186;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class _3186Test {
+    private static _3186.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _3186.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(6, solution1.maximumTotalDamage(new int[]{1, 1, 3, 4}));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(31, solution1.maximumTotalDamage(new int[]{5, 9, 2, 10, 2, 7, 10, 9, 3, 8}));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals(10, solution1.maximumTotalDamage(new int[]{7, 1, 6, 3}));
+    }
+
+}