Added tags 10-24, 864.

Author: javadev

src/main/kotlin/g0001_0100/s0010_regular_expression_matching/Solution.kt

@@ -1,30 +1,41 @@
 package g0001_0100.s0010_regular_expression_matching
 
 // #Hard #Top_100_Liked_Questions #Top_Interview_Questions #String #Dynamic_Programming #Recursion
+// #2022_03_29_Time_234_ms_(85.18%)_Space_35.8_MB_(82.10%)
 
 class Solution {
-    private lateinit var cache: Array<Array<Boolean?>>
-
     fun isMatch(s: String, p: String): Boolean {
-        cache = Array(s.length + 1) { arrayOfNulls(p.length + 1) }
-        return isMatch(s, p, 0, 0)
+        val n = s.length
+        val m = p.length
+        return solve(n - 1, m - 1, s, p)
     }
 
-    private fun isMatch(s: String, p: String, i: Int, j: Int): Boolean {
-        if (j == p.length) {
-            return i == s.length
+    private fun solve(i: Int, j: Int, s: String, p: String): Boolean {
+        if (j < 0) {
+            return i < 0
+        }
+        if (i < 0) {
+            return p[j] == '*' && solve(i, j - 2, s, p)
         }
-        val result: Boolean
-        if (cache[i][j] != null) {
-            return cache[i][j]!!
+        // simple char matching
+        // if s char matchs with p char or it can be '.'
+        if (s[i] == p[j] || p[j] == '.') {
+            return solve(i - 1, j - 1, s, p)
         }
-        val firstMatch = i < s.length && (s[i] == p[j] || p[j] == '.')
-        result = if (j + 1 < p.length && p[j + 1] == '*') {
-            firstMatch && isMatch(s, p, i + 1, j) || isMatch(s, p, i, j + 2)
+        return if (p[j] == '*') {
+            // if s char matches with p char or it can be '.'
+            if (s[i] == p[j - 1] || p[j - 1] == '.') {
+                solve(i - 1, j, s, p) || solve(i, j - 2, s, p)
+            } else {
+                solve(
+                    i,
+                    j - 2,
+                    s,
+                    p
+                )
+            }
         } else {
-            firstMatch && isMatch(s, p, i + 1, j + 1)
+            false
         }
-        cache[i][j] = result
-        return result
     }
 }

src/main/kotlin/g0001_0100/s0011_container_with_most_water/Solution.kt

@@ -1,7 +1,7 @@
 package g0001_0100.s0011_container_with_most_water
 
 // #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Greedy #Two_Pointers
-// #2022_02_17_Time_3_ms_(91.89%)_Space_81.7_MB_(5.91%)
+// #Algorithm_II_Day_4_Two_Pointers #2022_03_29_Time_635_ms_(64.22%)_Space_82.6_MB_(63.74%)
 
 class Solution {
     fun maxArea(height: IntArray): Int {

src/main/kotlin/g0001_0100/s0012_integer_to_roman/Solution.kt

@@ -1,6 +1,6 @@
 package g0001_0100.s0012_integer_to_roman
 
-// #Medium #String #Hash_Table #Math #2022_02_17_Time_7_ms_(70.99%)_Space_44.8_MB_(31.56%)
+// #Medium #String #Hash_Table #Math #2022_03_29_Time_300_ms_(72.89%)_Space_43.3_MB_(41.90%)
 
 class Solution {
     fun intToRoman(num: Int): String? {

src/main/kotlin/g0001_0100/s0013_roman_to_integer/Solution.kt

@@ -1,7 +1,7 @@
 package g0001_0100.s0013_roman_to_integer
 
 // #Easy #Top_Interview_Questions #String #Hash_Table #Math
-// #2022_02_17_Time_5_ms_(82.08%)_Space_45_MB_(29.21%)
+// #2022_03_29_Time_293_ms_(78.06%)_Space_38.2_MB_(81.58%)
 
 class Solution {
     fun romanToInt(s: String): Int {

src/main/kotlin/g0001_0100/s0014_longest_common_prefix/Solution.kt

@@ -1,8 +1,8 @@
 package g0001_0100.s0014_longest_common_prefix
 
-// #Easy #Top_Interview_Questions #String
+// #Easy #Top_Interview_Questions #String #2022_03_29_Time_269_ms_(48.51%)_Space_34.8_MB_(98.92%)
 
-internal class Solution {
+class Solution {
     fun longestCommonPrefix(strs: Array<String>): String {
         if (strs.size < 1) {
             return ""

src/main/kotlin/g0001_0100/s0015_3sum/Solution.kt

@@ -1,7 +1,8 @@
 package g0001_0100.s0015_3sum
 
 // #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Sorting #Two_Pointers
-// #2022_02_17_Time_29_ms_(68.11%)_Space_59.7_MB_(23.79%)
+// #Data_Structure_II_Day_1_Array #Algorithm_II_Day_3_Two_Pointers
+// #2022_03_29_Time_1059_ms_(55.28%)_Space_77.6_MB_(79.97%)
 
 import java.util.Arrays
 import kotlin.collections.ArrayList

src/main/kotlin/g0001_0100/s0016_3sum_closest/Solution.kt

@@ -1,6 +1,6 @@
 package g0001_0100.s0016_3sum_closest
 
-// #Medium #Array #Sorting #Two_Pointers
+// #Medium #Array #Sorting #Two_Pointers #2022_03_29_Time_219_ms_(89.56%)_Space_38_MB_(78.02%)
 
 import java.util.Arrays
 

src/main/kotlin/g0001_0100/s0017_letter_combinations_of_a_phone_number/Solution.kt

@@ -1,6 +1,8 @@
 package g0001_0100.s0017_letter_combinations_of_a_phone_number
 
 // #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Hash_Table #Backtracking
+// #Algorithm_II_Day_11_Recursion_Backtracking
+// #2022_03_29_Time_132_ms_(100.00%)_Space_35.3_MB_(96.41%)
 
 class Solution {
     fun letterCombinations(digits: String): List<String> {

src/main/kotlin/g0001_0100/s0018_4sum/Solution.kt

@@ -1,55 +1,55 @@
 package g0001_0100.s0018_4sum
 
-// #Medium #Array #Sorting #Two_Pointers
+// #Medium #Array #Sorting #Two_Pointers #2022_03_29_Time_467_ms_(81.25%)_Space_44.4_MB_(82.81%)
 
 import java.util.Arrays
 
 class Solution {
-    fun fourSum(nums: IntArray, target: Int): List<List<Int>> {
-        val list: MutableList<List<Int>> = ArrayList()
+    fun fourSum(nums: IntArray, target: Int): List<List<Int?>?> {
+        var list: MutableList<List<Int?>?> = ArrayList()
+        var i: Int
+        var j: Int
+        var k: Int
+        var l: Int
         Arrays.sort(nums)
-        val n = nums.size
-        if (n == 0) {
-            return list
-        }
-        for (a in 0 until n - 3) {
-            if (a > 0 && nums[a] == nums[a - 1]) {
+        i = 0
+        while (i < nums.size - 3) {
+            if (i > 0 && nums[i] == nums[i - 1]) {
+                i++
                 continue
             }
-            for (d in n - 1 downTo a + 2 + 1) {
-                if (d < n - 1 && nums[d] == nums[d + 1]) {
-                    continue
-                }
-                var b = a + 1
-                var c = d - 1
-                val min = nums[a] + nums[d] + nums[b] + nums[b + 1]
-                if (min > target) {
+            j = i + 1
+            while (j < nums.size - 2) {
+                if (j > i + 1 && nums[j] == nums[j - 1]) {
+                    j++
                     continue
                 }
-                val max = nums[a] + nums[d] + nums[c] + nums[c - 1]
-                if (max < target) {
-                    break
-                }
-                while (c > b) {
-                    val sum = nums[a] + nums[b] + nums[c] + nums[d]
-                    if (sum > target) {
-                        c--
-                    } else if (sum < target) {
-                        b++
-                    } else {
-                        list.add(Arrays.asList(nums[a], nums[b], nums[c], nums[d]))
-                        while (c > b && nums[b] == nums[b + 1]) {
-                            b++
-                        }
-                        while (c > b && nums[c] == nums[c - 1]) {
-                            c--
+                k = j + 1
+                l = nums.size - 1
+                while (k < l) {
+                    val sum = nums[i] + nums[j] + nums[k] + nums[l]
+                    if (sum == target) {
+                        val l1 = ArrayList<Int?>()
+                        l1.add(nums[i])
+                        l1.add(nums[j])
+                        l1.add(nums[k])
+                        l1.add(nums[l])
+                        list.add(l1)
+                        l--
+                        if (k < l && nums[l] == nums[l + 1]) {
+                            l--
                         }
-                        b++
-                        c--
+                    } else if (sum > target) {
+                        l--
+                    } else {
+                        k++
                     }
                 }
+                j++
             }
+            i++
         }
+        list = ArrayList(LinkedHashSet(list))
         return list
     }
 }

src/main/kotlin/g0001_0100/s0019_remove_nth_node_from_end_of_list/Solution.kt

@@ -1,16 +1,27 @@
 package g0001_0100.s0019_remove_nth_node_from_end_of_list
 
 // #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Two_Pointers #Linked_List
+// #Algorithm_I_Day_5_Two_Pointers #2022_03_29_Time_172_ms_(85.17%)_Space_35_MB_(74.14%)
 
 import com_github_leetcode.ListNode
 
+/*
+ * Example:
+ * var li = ListNode(5)
+ * var v = li.`val`
+ * Definition for singly-linked list.
+ * class ListNode(var `val`: Int) {
+ *     var next: ListNode? = null
+ * }
+ */
 class Solution {
-    var n = 0
+    private var n = 0
+
     fun removeNthFromEnd(head: ListNode?, n: Int): ListNode? {
         this.n = n
         val node = ListNode(0, head)
         removeNth(node)
-        return node?.next
+        return node.next
     }
 
     private fun removeNth(node: ListNode?) {
@@ -20,7 +31,7 @@ class Solution {
         removeNth(node.next)
         n--
         if (n == 0) {
-            node.next = node?.next?.next
+            node.next = node.next?.next
         }
     }
 }

src/main/kotlin/g0001_0100/s0020_valid_parentheses/Solution.kt

@@ -1,7 +1,7 @@
 package g0001_0100.s0020_valid_parentheses
 
 // #Easy #Top_100_Liked_Questions #Top_Interview_Questions #String #Stack
-// #2022_02_17_Time_3_ms_(53.65%)_Space_42.1_MB_(17.58%)
+// #Data_Structure_I_Day_9_Stack_Queue #2022_03_29_Time_196_ms_(71.08%)_Space_34.7_MB_(40.99%)
 
 import java.util.Stack
 

src/main/kotlin/g0001_0100/s0021_merge_two_sorted_lists/Solution.kt

@@ -1,7 +1,8 @@
 package g0001_0100.s0021_merge_two_sorted_lists
 
 // #Easy #Top_100_Liked_Questions #Top_Interview_Questions #Linked_List #Recursion
-// #2022_02_17_Time_1_ms_(61.88%)_Space_42.8_MB_(22.76%)
+// #Data_Structure_I_Day_7_Linked_List #Algorithm_I_Day_10_Recursion_Backtracking
+// #2022_03_29_Time_148_ms_(99.90%)_Space_35.5_MB_(81.70%)
 
 import com_github_leetcode.ListNode
 

src/main/kotlin/g0001_0100/s0022_generate_parentheses/Solution.kt

@@ -1,7 +1,8 @@
 package g0001_0100.s0022_generate_parentheses
 
 // #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Dynamic_Programming
-// #Backtracking #2022_02_17_Time_1_ms_(87.91%)_Space_43.6_MB_(19.97%)
+// #Backtracking #Algorithm_II_Day_11_Recursion_Backtracking
+// #2022_03_29_Time_210_ms_(78.51%)_Space_37.3_MB_(76.72%)
 
 class Solution {
     fun generateParenthesis(n: Int): List<String> {

src/main/kotlin/g0001_0100/s0023_merge_k_sorted_lists/Solution.kt

@@ -1,7 +1,7 @@
 package g0001_0100.s0023_merge_k_sorted_lists
 
 // #Hard #Top_100_Liked_Questions #Top_Interview_Questions #Heap_Priority_Queue #Linked_List
-// #Divide_and_Conquer #Merge_Sort #2022_02_18_Time_1_ms_(100.00%)_Space_43.9_MB_(75.94%)
+// #Divide_and_Conquer #Merge_Sort #2022_03_29_Time_323_ms_(75.14%)_Space_43.3_MB_(68.27%)
 
 import com_github_leetcode.ListNode
 

src/main/kotlin/g0001_0100/s0024_swap_nodes_in_pairs/Solution.kt

@@ -1,6 +1,7 @@
 package g0001_0100.s0024_swap_nodes_in_pairs
 
-// #Medium #Linked_List #Recursion #2022_02_18_Time_0_ms_(100.00%)_Space_41.9_MB_(22.86%)
+// #Medium #Linked_List #Recursion #Data_Structure_II_Day_12_Linked_List
+// #2022_03_29_Time_173_ms_(83.13%)_Space_34.6_MB_(41.93%)
 
 import com_github_leetcode.ListNode
 

src/main/kotlin/g0801_0900/s0864_shortest_path_to_get_all_keys/Solution.kt

@@ -1,5 +1,8 @@
 package g0801_0900.s0864_shortest_path_to_get_all_keys
 
+// #Hard #Breadth_First_Search #Bit_Manipulation
+// #2022_03_29_Time_176_ms_(100.00%)_Space_36.3_MB_(100.00%)
+
 import java.util.LinkedList
 import java.util.Queue