update

Author: OneCodeMonkey

leetcode_solved/leetcode_2364_Count_Number_of_Bad_Pairs.java

@@ -0,0 +1,20 @@
+// Runtime 38 ms Beats 63.24% 
+// Memory 56.93 MB Beats 82.65%
+// Prefix sum & tricky.
+// T:O(n), S:O(n)
+// 
+class Solution {
+    public long countBadPairs(int[] nums) {
+        HashMap<Integer, Integer> diffCount = new HashMap<>();
+        int len = nums.length;
+        long ret = 0;
+        for (int i = 0; i < len; i++) {
+            diffCount.merge(nums[i] - i, 1, Integer::sum);
+        }
+        for (int i = 0; i < len; i++) {
+            ret += len - diffCount.get(nums[i] - i);
+        }
+
+        return ret / 2;
+    }
+}

leetcode_solved/leetcode_2698_Find_the_Punishment_Number_of_an_Integer.java

@@ -0,0 +1,29 @@
+// Runtime 5 ms Beats 98.43% 
+// Memory 40.90 MB Beats 82.76%
+// Recursion & some tricky.
+// T:O(n * (2^logn)), S:O(1)
+// 
+class Solution {
+    public int punishmentNumber(int n) {
+        int ret = 0;
+        for (int i = 1; i <= n; i++) {
+            if (canPart(i * i, i)) {
+                ret += i * i;
+            }
+        }
+
+        return ret;
+    }
+
+    private boolean canPart(int square, int i) {
+        if (i < 0 || square < i) {
+            return false;
+        }
+        if (square == i) {
+            return true;
+        }
+
+        return canPart(square / 10, i - (square % 10)) || canPart(square / 100, i - (square % 100))
+                || canPart(square / 1000, i - (square % 1000));
+    }
+}

leetcode_solved/leetcode_3452_Sum_of_Good_Numbers.java

@@ -0,0 +1,18 @@
+// Runtime 1 ms Beats 100.00% 
+// Memory 44.11 MB Beats 100.00%
+// .
+// T:O(n), S:O(1)
+// 
+class Solution {
+    public int sumOfGoodNumbers(int[] nums, int k) {
+        int len = nums.length, ret = 0;
+        for (int i = 0; i < len; i++) {
+            if ((i - k < 0 || (i - k >= 0 && nums[i] > nums[i - k])) &&
+                    (i + k >= len || (i + k < len && nums[i] > nums[i + k]))) {
+                ret += nums[i];
+            }
+        }
+
+        return ret;
+    }
+}