Commit8b9c165

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add a solution for 24

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+45

-2

lines changed

src
- main/java/com/fishercoder/solutions
  - _24.java
- test/java/com/fishercoder
  - _24Test.java

+45

-2

lines changed

Lines changed: 31 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -4,6 +4,9 @@`
`4`	`4`
`5`	`5`	`publicclass_24 {`
`6`	`6`	`publicstaticclassSolution1 {`
	`7`	`+/**`
	`8`	`+ * Recursive solution.`
	`9`	`+ */`
`7`	`10`	`publicListNodeswapPairs(ListNodehead) {`
`8`	`11`	`if (head ==null \|\|head.next ==null) {`
`9`	`12`	`returnhead;`
`@@ -16,4 +19,32 @@ public ListNode swapPairs(ListNode head) {`
`16`	`19`	`}`
`17`	`20`	`}`
`18`	`21`
	`22`	`+publicstaticclassSolution2 {`
	`23`	`+/**`
	`24`	`+ * Iterative approach:`
	`25`	`+ * My completely original on 10/24/2021.`
	`26`	`+ */`
	`27`	`+publicListNodeswapPairs(ListNodehead) {`
	`28`	`+ListNodepre =newListNode(-1);`
	`29`	`+pre.next =head;`
	`30`	`+ListNodetmp =pre;`
	`31`	`+while (head !=null) {`
	`32`	`+ListNodethird;`
	`33`	`+ListNodefirst =head;`
	`34`	`+ListNodesecond =head.next;`
	`35`	`+if (second ==null) {`
	`36`	`+break;`
	`37`	`+ }else {`
	`38`	`+third =head.next.next;`
	`39`	`+second.next =first;`
	`40`	`+first.next =third;`
	`41`	`+tmp.next =second;`
	`42`	`+tmp =tmp.next.next;`
	`43`	`+ }`
	`44`	`+head =third;`
	`45`	`+ }`
	`46`	`+returnpre.next;`
	`47`	`+ }`
	`48`	`+ }`
	`49`	`+`
`19`	`50`	`}`

Lines changed: 14 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,27 +1,39 @@`
`1`	`1`	`packagecom.fishercoder;`
`2`	`2`
`3`	`3`	`importcom.fishercoder.common.classes.ListNode;`
`4`		`-importcom.fishercoder.common.utils.CommonUtils;`
`5`	`4`	`importcom.fishercoder.common.utils.LinkedListUtils;`
`6`	`5`	`importcom.fishercoder.solutions._24;`
`7`	`6`	`importorg.junit.BeforeClass;`
`8`	`7`	`importorg.junit.Test;`
`9`	`8`
`10`	`9`	`importjava.util.Arrays;`
`11`	`10`
	`11`	`+importstaticorg.junit.Assert.assertEquals;`
	`12`	`+`
`12`	`13`	`publicclass_24Test {`
`13`	`14`	`privatestatic_24.Solution1solution1;`
	`15`	`+privatestatic_24.Solution2solution2;`
`14`	`16`	`privatestaticListNodehead;`
	`17`	`+privatestaticListNodeexpected;`
`15`	`18`
`16`	`19`	`@BeforeClass`
`17`	`20`	`publicstaticvoidsetup() {`
`18`	`21`	`solution1 =new_24.Solution1();`
	`22`	`+solution2 =new_24.Solution2();`
`19`	`23`	`}`
`20`	`24`
`21`	`25`	`@Test`
`22`	`26`	`publicvoidtest1() {`
`23`	`27`	`head =LinkedListUtils.createSinglyLinkedList(Arrays.asList(1,2,3,4));`
`24`		`-CommonUtils.printList(solution1.swapPairs(head));`
	`28`	`+expected =LinkedListUtils.createSinglyLinkedList(Arrays.asList(2,1,4,3));`
	`29`	`+assertEquals(expected,solution1.swapPairs(head));`
	`30`	`+ }`
	`31`	`+`
	`32`	`+@Test`
	`33`	`+publicvoidtest2() {`
	`34`	`+head =LinkedListUtils.createSinglyLinkedList(Arrays.asList(1,2,3,4));`
	`35`	`+expected =LinkedListUtils.createSinglyLinkedList(Arrays.asList(2,1,4,3));`
	`36`	`+assertEquals(expected,solution2.swapPairs(head));`
`25`	`37`	`}`
`26`	`38`
`27`	`39`	`}`

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