update 20 java, cheatsheet, progress

data/progress.txt

@@ -1,4 +1,4 @@
-20240527: 21
+20240527: 21,20
 20240526: 417(again),33,153,152
 20240525: 424,297(todo),295(todo),39
 20240524: 55,54(todo),53(again),435(again),49,48(todo),300(again)

data/to_review.txt

@@ -1,4 +1,4 @@
-2024-07-21 -> ['21']
+2024-07-21 -> ['21,20']
 2024-07-20 -> ['417(again),33,153,152']
 2024-07-19 -> ['424,297(todo),295(todo),39']
 2024-07-18 -> ['55,54(todo),53(again),435(again),49,48(todo),300(again)']
@@ -16,7 +16,7 @@
 2024-07-06 -> ['371']
 2024-07-05 -> ['121,252']
 2024-07-04 -> ['125']
-2024-06-30 -> ['21']
+2024-06-30 -> ['21,20']
 2024-06-29 -> ['417(again),33,153,152']
 2024-06-28 -> ['424,297(todo),295(todo),39']
 2024-06-27 -> ['55,54(todo),53(again),435(again),49,48(todo),300(again)']
@@ -29,27 +29,27 @@
 2024-06-20 -> ['347,253(todo),91(todo),217']
 2024-06-19 -> ['226,98,253(todo)']
 2024-06-18 -> ['104,230,102,100']
-2024-06-17 -> ['21', '105,106']
+2024-06-17 -> ['21,20', '105,106']
 2024-06-16 -> ['417(again),33,153,152', '242,235']
 2024-06-15 -> ['424,297(todo),295(todo),39', '371']
 2024-06-14 -> ['55,54(todo),53(again),435(again),49,48(todo),300(again)', '121,252']
 2024-06-13 -> ['56', '125']
 2024-06-12 -> ['62,572,57']
 2024-06-11 -> ['322,191,190']
 2024-06-10 -> ['73,200,70,323(again)']
-2024-06-09 -> ['21', '207,79,206,213,198']
+2024-06-09 -> ['21,20', '207,79,206,213,198']
 2024-06-08 -> ['417(again),33,153,152', '212(todo),211,338,208(again)']
 2024-06-07 -> ['424,297(todo),295(todo),39', '347,253(todo),91(todo),217']
 2024-06-06 -> ['55,54(todo),53(again),435(again),49,48(todo),300(again)', '226,98,253(todo)']
 2024-06-05 -> ['56', '104,230,102,100']
-2024-06-04 -> ['21', '62,572,57', '105,106']
+2024-06-04 -> ['21,20', '62,572,57', '105,106']
 2024-06-03 -> ['417(again),33,153,152', '322,191,190', '242,235']
 2024-06-02 -> ['424,297(todo),295(todo),39', '73,200,70,323(again)', '371']
-2024-06-01 -> ['21', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '207,79,206,213,198', '121,252']
+2024-06-01 -> ['21,20', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '207,79,206,213,198', '121,252']
 2024-05-31 -> ['417(again),33,153,152', '56', '212(todo),211,338,208(again)', '125']
-2024-05-30 -> ['21', '424,297(todo),295(todo),39', '62,572,57', '347,253(todo),91(todo),217']
-2024-05-29 -> ['21', '417(again),33,153,152', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '322,191,190', '226,98,253(todo)']
-2024-05-28 -> ['21', '417(again),33,153,152', '424,297(todo),295(todo),39', '56', '73,200,70,323(again)', '104,230,102,100']
+2024-05-30 -> ['21,20', '424,297(todo),295(todo),39', '62,572,57', '347,253(todo),91(todo),217']
+2024-05-29 -> ['21,20', '417(again),33,153,152', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '322,191,190', '226,98,253(todo)']
+2024-05-28 -> ['21,20', '417(again),33,153,152', '424,297(todo),295(todo),39', '56', '73,200,70,323(again)', '104,230,102,100']
 2024-05-27 -> ['417(again),33,153,152', '424,297(todo),295(todo),39', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '62,572,57', '207,79,206,213,198', '105,106']
 2024-05-26 -> ['424,297(todo),295(todo),39', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '56', '322,191,190', '212(todo),211,338,208(again)', '242,235']
 2024-05-25 -> ['55,54(todo),53(again),435(again),49,48(todo),300(again)', '56', '62,572,57', '73,200,70,323(again)', '347,253(todo),91(todo),217', '371']

doc/cheatsheet/java_trick.md

@@ -709,4 +709,14 @@ return check_(root, smallest_val, biggest_val);
 
 // LC 338
 
+```
+
+### 2-5) Init Queue
+
+- https://stackoverflow.com/questions/4626812/how-do-i-instantiate-a-queue-object-in-java
+
+- A Queue is an `interface`, which means you cannot construct a Queue directly.
+- Consinder use one of below implementation:
+```
+    AbstractQueue, ArrayBlockingQueue, ArrayDeque, ConcurrentLinkedQueue, DelayQueue, LinkedBlockingQueue, LinkedList, PriorityBlockingQueue, PriorityQueue, or SynchronousQueue.
 ```

leetcode_java/src/main/java/LeetCodeJava/Stack/ValidParentheses.java

@@ -5,6 +5,7 @@
 // https://www.softwaretestinghelp.com/java-queue-interface/
 
 import java.util.HashMap;
+import java.util.Map;
 import java.util.Stack;
 
 public class ValidParentheses {
@@ -13,6 +14,40 @@ public class ValidParentheses {
     // IDEA : STACK + DICT
     public boolean isValid(String s) {
 
+        if (s == null || s.length() == 0){
+            return true;
+        }
+
+        Map<String, String> map = new HashMap<>();
+        map.put("(", ")");
+        map.put("{", "}");
+        map.put("[", "]");
+
+        /** NOTE !!! use stack here, FILO */
+        Stack<String> stack = new Stack<>();
+
+        for (String x : s.split("")){
+            //System.out.println("x = " + x + " stack = " + stack);
+            if (map.containsKey(x)){
+                stack.add(x);
+            }else{
+                if (stack.isEmpty()){
+                    return false;
+                }
+                String last = stack.pop();
+                if (!map.get(last).equals(x)){
+                    return false;
+                }
+            }
+        }
+
+        return stack.isEmpty();
+    }
+
+    // V0'
+    // IDEA : STACK + DICT
+    public boolean isValid_0(String s) {
+
         if (s.length() % 2 != 0){
             return false;
         }

leetcode_java/src/main/java/dev/workspace3.java

@@ -2312,4 +2312,36 @@ public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
         return root.next;
     }
 
+    // LC 20
+    public boolean isValid(String s) {
+
+        if (s == null || s.length() == 0){
+            return true;
+        }
+
+        Map<String, String> map = new HashMap<>();
+        map.put("(", ")");
+        map.put("{", "}");
+        map.put("[", "]");
+
+        Stack<String> stack = new Stack<>(); // TODO : check
+
+        for (String x : s.split("")){
+            System.out.println("x = " + x + " stack = " + stack);
+            if (map.containsKey(x)){
+                stack.add(x);
+            }else{
+                if (stack.isEmpty()){
+                    return false;
+                }
+                String last = stack.pop();
+                if (!map.get(last).equals(x)){
+                    return false;
+                }
+            }
+        }
+
+        return stack.isEmpty();
+    }
+
 }