3186. Maximum Total Damage With Spell Casting

October 2025/october_12.java

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+class Solution {
+  public long maximumTotalDamage(int[] power) {
+    Map<Integer, Integer> count = new HashMap<>();
+
+    for (final int damage : power)
+      count.merge(damage, 1, Integer::sum);
+
+    List<Integer> uniqueDamages = getSortedUniqueDamages(count);
+    final int n = uniqueDamages.size();
+    // dp[i][k] := the maximum damage using uniqueDamages[0..i], where k
+    // indicates if the i-th damage is used
+    long[][] dp = new long[n][2];
+
+    for (int i = 0; i < n; ++i) {
+      final int damage = uniqueDamages.get(i);
+      if (i == 0) {
+        dp[0][0] = 0;
+        dp[0][1] = (long) damage * count.get(damage);
+        continue;
+      }
+      dp[i][0] = Math.max(dp[i - 1][0], dp[i - 1][1]);
+      dp[i][1] = (long) damage * count.get(damage);
+      if (i >= 1 && uniqueDamages.get(i - 1) != damage - 1 &&
+          uniqueDamages.get(i - 1) != damage - 2) {
+        dp[i][1] += Math.max(dp[i - 1][0], dp[i - 1][1]);
+      } else if (i >= 2 && uniqueDamages.get(i - 2) != damage - 2) {
+        dp[i][1] += Math.max(dp[i - 2][0], dp[i - 2][1]);
+      } else if (i >= 3) {
+        dp[i][1] += Math.max(dp[i - 3][0], dp[i - 3][1]);
+      }
+    }
+
+    return Math.max(dp[n - 1][0], dp[n - 1][1]);
+  }
+
+  private List<Integer> getSortedUniqueDamages(Map<Integer, Integer> count) {
+    List<Integer> uniqueDamages = new ArrayList<>(count.keySet());
+    Collections.sort(uniqueDamages);
+    return uniqueDamages;
+  }
+}