update 636

Author: fishercoder1534

Diff for: src/main/java/com/fishercoder/solutions/_636.java

@@ -6,31 +6,27 @@
 
 public class _636 {
     public static class Solution1 {
-        /**
-         * Based on the example, it's difficult to see how function 2 executes 4 units of time, actually
-         * we can add 1 to all end times to make it easier to understand and AC'ed.
-         */
         public int[] exclusiveTime(int n, List<String> logs) {
             /**Stack is the way to go:
-             * we keep pushing the logId onto the stack whenever we just encounter this logId's start timestamp,
-             * we'll pop this logId only when we encounter this logId's end timestamp.
-             * Meanwhile, we keep a counter called prevTime,
-             * whenever the stack is not empty, we'll always deduct prevTime from the last logId on the stack.*/
+             * 1. we keep pushing the logId onto the stack whenever we just encounter this logId's start timestamp,
+             * 2. we'll pop this logId only when we encounter this logId's end timestamp.
+             * 3. Meanwhile, we keep a counter called prevTime,
+             * 4. whenever the stack is not empty, we'll always deduct prevTime from the last logId on the stack.*/
             Deque<Integer> stack = new LinkedList<>();
             int[] result = new int[n];
             int prevTime = 0;
             for (String log : logs) {
                 String[] parts = log.split(":");
                 if (!stack.isEmpty()) {
-                    result[stack.peek()] += Integer.parseInt(parts[2]) - prevTime;
+                    result[stack.peekLast()] += Integer.parseInt(parts[2]) - prevTime;
                 }
                 prevTime = Integer.parseInt(parts[2]);
                 if (parts[1].equals("start")) {
-                    stack.addFirst(Integer.parseInt(parts[0]));//i.e. stack.push()
+                    stack.addLast(Integer.parseInt(parts[0]));
                 } else {
+                    //remember to have result plus 1, i.e. when a task starts at 2, ends at 5, it should be 5 -2 + 1 = 4
                     prevTime++;
-                    //remember to have result pluse 1 to match the problem AC criteria
-                    result[stack.pollFirst()]++;//i.e. stack.pop()
+                    result[stack.pollLast()]++;
                 }
             }
             return result;

Diff for: src/test/java/com/fishercoder/_636Test.java

@@ -0,0 +1,24 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._636;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+public class _636Test {
+    private static _636.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _636.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertArrayEquals(new int[]{3, 4}, solution1.exclusiveTime(2, Arrays.asList("0:start:0", "1:start:2", "1:end:5", "0:end:6")));
+    }
+
+}