add a solution for 376

fishercoder1534 · fishercoder1534 · commit 2793ac5c7a9c · 2021-03-18T10:33:35.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_376.java b/src/main/java/com/fishercoder/solutions/_376.java
@@ -3,6 +3,32 @@
 public class _376 {
 
     public static class Solution1 {
+        /**
+         * credit: https://leetcode.com/problems/wiggle-subsequence/discuss/84843/Easy-understanding-DP-solution-with-O(n)-Java-version
+         */
+        public int wiggleMaxLength(int[] nums) {
+            int len = nums.length;
+            int[] up = new int[len];
+            int[] down = new int[len];
+            up[0] = 1;
+            down[0] = 1;
+            for (int i = 1; i < len; i++) {
+                if (nums[i] > nums[i - 1]) {
+                    up[i] = down[i - 1] + 1;
+                    down[i] = down[i - 1];
+                } else if (nums[i] < nums[i - 1]) {
+                    down[i] = up[i - 1] + 1;
+                    up[i] = up[i - 1];
+                } else {
+                    up[i] = up[i - 1];
+                    down[i] = down[i - 1];
+                }
+            }
+            return Math.max(down[len - 1], up[len - 1]);
+        }
+    }
+
+    public static class Solution2 {
         public int wiggleMaxLength(int[] nums) {
             if (nums.length < 2) {
                 return nums.length;
@@ -12,7 +38,7 @@ public int wiggleMaxLength(int[] nums) {
             for (int i = 2; i < nums.length; i++) {
                 int diff = nums[i] - nums[i - 1];
                 /**ATTN: prevDiff could be zero. e.g. [3,3,3,2,5]
-                 * but diff needs to exactly greater than zero*/
+                 * but diff needs to be exactly greater than zero*/
                 if ((prevDiff <= 0 && diff > 0) || (prevDiff >= 0) && diff < 0) {
                     count++;
                     prevDiff = diff;
diff --git a/src/test/java/com/fishercoder/_376Test.java b/src/test/java/com/fishercoder/_376Test.java
@@ -7,80 +7,80 @@
 import static org.junit.Assert.assertEquals;
 
 public class _376Test {
-  private static _376.Solution1 solution1;
-  private static int[] nums;
+    private static _376.Solution1 solution1;
+    private static int[] nums;
 
-  @BeforeClass
-  public static void setup() {
-    solution1 = new _376.Solution1();
-  }
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _376.Solution1();
+    }
 
-  @Test
-  public void test1() {
-    nums = new int[] {1, 7, 4, 9, 2, 5};
-    assertEquals(6, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test1() {
+        nums = new int[]{1, 7, 4, 9, 2, 5};
+        assertEquals(6, solution1.wiggleMaxLength(nums));
+    }
 
-  @Test
-  public void test2() {
-    nums = new int[] {1, 17, 5, 10, 13, 15, 10, 5, 16, 8};
-    assertEquals(7, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test2() {
+        nums = new int[]{1, 17, 5, 10, 13, 15, 10, 5, 16, 8};
+        assertEquals(7, solution1.wiggleMaxLength(nums));
+    }
 
-  @Test
-  public void test3() {
-    nums = new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9};
-    assertEquals(2, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test3() {
+        nums = new int[]{1, 2, 3, 4, 5, 6, 7, 8, 9};
+        assertEquals(2, solution1.wiggleMaxLength(nums));
+    }
 
-  @Test
-  public void test4() {
-    nums =
-        new int[] {33, 53, 12, 64, 50, 41, 45, 21, 97, 35, 47, 92, 39, 0, 93, 55, 40, 46, 69, 42, 6,
-            95, 51, 68, 72, 9, 32, 84, 34, 64, 6, 2, 26, 98, 3, 43, 30, 60, 3, 68, 82, 9, 97, 19,
-            27, 98, 99, 4, 30, 96, 37, 9, 78, 43, 64, 4, 65, 30, 84, 90, 87, 64, 18, 50, 60, 1, 40,
-            32, 48, 50, 76, 100, 57, 29, 63, 53, 46, 57, 93, 98, 42, 80, 82, 9, 41, 55, 69, 84, 82,
-            79, 30, 79, 18, 97, 67, 23, 52, 38, 74, 15};
-    assertEquals(67, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test4() {
+        nums =
+                new int[]{33, 53, 12, 64, 50, 41, 45, 21, 97, 35, 47, 92, 39, 0, 93, 55, 40, 46, 69, 42, 6,
+                        95, 51, 68, 72, 9, 32, 84, 34, 64, 6, 2, 26, 98, 3, 43, 30, 60, 3, 68, 82, 9, 97, 19,
+                        27, 98, 99, 4, 30, 96, 37, 9, 78, 43, 64, 4, 65, 30, 84, 90, 87, 64, 18, 50, 60, 1, 40,
+                        32, 48, 50, 76, 100, 57, 29, 63, 53, 46, 57, 93, 98, 42, 80, 82, 9, 41, 55, 69, 84, 82,
+                        79, 30, 79, 18, 97, 67, 23, 52, 38, 74, 15};
+        assertEquals(67, solution1.wiggleMaxLength(nums));
+    }
 
-  @Test
-  public void test5() {
-    nums = new int[] {3, 3, 3, 2, 5};
-    assertEquals(3, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test5() {
+        nums = new int[]{3, 3, 3, 2, 5};
+        assertEquals(3, solution1.wiggleMaxLength(nums));
+    }
 
-  @Test
-  public void test6() {
-    nums =
-        new int[] {372, 492, 288, 399, 81, 2, 320, 94, 416, 469, 427, 117, 265, 357, 399, 456, 496,
-            337, 355, 219, 475, 295, 457, 350, 490, 470, 281, 127, 131, 36, 430, 412, 442, 174, 128,
-            253, 1, 56, 306, 295, 340, 73, 253, 130, 259, 223, 14, 79, 409, 384, 209, 151, 317, 441,
-            156, 275, 140, 224, 128, 250, 290, 191, 161, 472, 477, 125, 470, 230, 321, 5, 311, 23,
-            27, 248, 138, 284, 215, 356, 320, 194, 434, 136, 221, 273, 450, 440, 28, 179, 36, 386,
-            482, 203, 24, 8, 391, 21, 500, 484, 135, 348, 292, 396, 145, 443, 406, 61, 212, 480,
-            455, 78, 309, 318, 84, 474, 209, 225, 177, 356, 227, 263, 181, 476, 478, 151, 494, 395,
-            23, 114, 395, 429, 450, 247, 245, 150, 354, 230, 100, 172, 454, 155, 189, 33, 290, 187,
-            443, 123, 59, 358, 241, 141, 39, 196, 491, 381, 157, 157, 134, 431, 295, 20, 123, 118,
-            207, 199, 317, 188, 267, 335, 315, 308, 115, 321, 56, 52, 253, 492, 97, 374, 398, 272,
-            74, 206, 109, 172, 471, 55, 452, 452, 329, 367, 372, 252, 99, 62, 122, 287, 320, 325,
-            307, 481, 316, 378, 87, 97, 457, 21, 312, 249, 354, 286, 196, 43, 170, 500, 265, 253,
-            19, 480, 438, 113, 473, 247, 257, 33, 395, 456, 246, 310, 469, 408, 112, 385, 53, 449,
-            117, 122, 210, 286, 149, 20, 364, 372, 71, 26, 155, 292, 16, 72, 384, 160, 79, 241, 346,
-            230, 15, 427, 96, 95, 59, 151, 325, 490, 223, 131, 81, 294, 18, 70, 171, 339, 14, 40,
-            463, 421, 355, 123, 408, 357, 202, 235, 390, 344, 198, 98, 361, 434, 174, 216, 197, 274,
-            231, 85, 494, 57, 136, 258, 134, 441, 477, 456, 318, 155, 138, 461, 65, 426, 162, 90,
-            342, 284, 374, 204, 464, 9, 280, 391, 491, 231, 298, 284, 82, 417, 355, 356, 207, 367,
-            262, 244, 283, 489, 477, 143, 495, 472, 372, 447, 322, 399, 239, 450, 168, 202, 89, 333,
-            276, 199, 416, 490, 494, 488, 137, 327, 113, 189, 430, 320, 197, 120, 71, 262, 31, 295,
-            218, 74, 238, 169, 489, 308, 300, 260, 397, 308, 328, 267, 419, 84, 357, 486, 289, 312,
-            230, 64, 468, 227, 268, 28, 243, 267, 254, 153, 407, 399, 346, 385, 77, 297, 273, 484,
-            366, 482, 491, 368, 221, 423, 107, 272, 98, 309, 426, 181, 320, 77, 185, 382, 478, 398,
-            476, 22, 328, 450, 299, 211, 285, 62, 344, 484, 395, 466, 291, 487, 301, 407, 28, 295,
-            36, 429, 99, 462, 240, 124, 261, 387, 30, 362, 161, 156, 184, 188, 99, 377, 392, 442,
-            300, 98, 285, 312, 312, 365, 415, 367, 105, 81, 378, 413, 43, 326, 490, 320, 266, 390,
-            53, 327, 75, 332, 454, 29, 370, 392, 360, 1, 335, 355, 344, 120, 417, 455, 93, 60, 256,
-            451, 188, 161, 388, 338, 238, 26, 275, 340, 109, 185};
-    assertEquals(334, solution1.wiggleMaxLength(nums));
-  }
+    @Test
+    public void test6() {
+        nums =
+                new int[]{372, 492, 288, 399, 81, 2, 320, 94, 416, 469, 427, 117, 265, 357, 399, 456, 496,
+                        337, 355, 219, 475, 295, 457, 350, 490, 470, 281, 127, 131, 36, 430, 412, 442, 174, 128,
+                        253, 1, 56, 306, 295, 340, 73, 253, 130, 259, 223, 14, 79, 409, 384, 209, 151, 317, 441,
+                        156, 275, 140, 224, 128, 250, 290, 191, 161, 472, 477, 125, 470, 230, 321, 5, 311, 23,
+                        27, 248, 138, 284, 215, 356, 320, 194, 434, 136, 221, 273, 450, 440, 28, 179, 36, 386,
+                        482, 203, 24, 8, 391, 21, 500, 484, 135, 348, 292, 396, 145, 443, 406, 61, 212, 480,
+                        455, 78, 309, 318, 84, 474, 209, 225, 177, 356, 227, 263, 181, 476, 478, 151, 494, 395,
+                        23, 114, 395, 429, 450, 247, 245, 150, 354, 230, 100, 172, 454, 155, 189, 33, 290, 187,
+                        443, 123, 59, 358, 241, 141, 39, 196, 491, 381, 157, 157, 134, 431, 295, 20, 123, 118,
+                        207, 199, 317, 188, 267, 335, 315, 308, 115, 321, 56, 52, 253, 492, 97, 374, 398, 272,
+                        74, 206, 109, 172, 471, 55, 452, 452, 329, 367, 372, 252, 99, 62, 122, 287, 320, 325,
+                        307, 481, 316, 378, 87, 97, 457, 21, 312, 249, 354, 286, 196, 43, 170, 500, 265, 253,
+                        19, 480, 438, 113, 473, 247, 257, 33, 395, 456, 246, 310, 469, 408, 112, 385, 53, 449,
+                        117, 122, 210, 286, 149, 20, 364, 372, 71, 26, 155, 292, 16, 72, 384, 160, 79, 241, 346,
+                        230, 15, 427, 96, 95, 59, 151, 325, 490, 223, 131, 81, 294, 18, 70, 171, 339, 14, 40,
+                        463, 421, 355, 123, 408, 357, 202, 235, 390, 344, 198, 98, 361, 434, 174, 216, 197, 274,
+                        231, 85, 494, 57, 136, 258, 134, 441, 477, 456, 318, 155, 138, 461, 65, 426, 162, 90,
+                        342, 284, 374, 204, 464, 9, 280, 391, 491, 231, 298, 284, 82, 417, 355, 356, 207, 367,
+                        262, 244, 283, 489, 477, 143, 495, 472, 372, 447, 322, 399, 239, 450, 168, 202, 89, 333,
+                        276, 199, 416, 490, 494, 488, 137, 327, 113, 189, 430, 320, 197, 120, 71, 262, 31, 295,
+                        218, 74, 238, 169, 489, 308, 300, 260, 397, 308, 328, 267, 419, 84, 357, 486, 289, 312,
+                        230, 64, 468, 227, 268, 28, 243, 267, 254, 153, 407, 399, 346, 385, 77, 297, 273, 484,
+                        366, 482, 491, 368, 221, 423, 107, 272, 98, 309, 426, 181, 320, 77, 185, 382, 478, 398,
+                        476, 22, 328, 450, 299, 211, 285, 62, 344, 484, 395, 466, 291, 487, 301, 407, 28, 295,
+                        36, 429, 99, 462, 240, 124, 261, 387, 30, 362, 161, 156, 184, 188, 99, 377, 392, 442,
+                        300, 98, 285, 312, 312, 365, 415, 367, 105, 81, 378, 413, 43, 326, 490, 320, 266, 390,
+                        53, 327, 75, 332, 454, 29, 370, 392, 360, 1, 335, 355, 344, 120, 417, 455, 93, 60, 256,
+                        451, 188, 161, 388, 338, 238, 26, 275, 340, 109, 185};
+        assertEquals(334, solution1.wiggleMaxLength(nums));
+    }
 }
