Commit b6bf510

author

Shuo

authored

Merge pull request #377 from openset/develop

Add: Linked List Cycle

2 parents 1ac41fa + 7177ee6 commit b6bf510Copy full SHA for b6bf510

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Lines changed: 20 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1 +1,21 @@`
`1`	`1`	`package linked_list_cycle`
	`2`	`+`
	`3`	`+import . "github.com/openset/leetcode/internal/kit"`
	`4`	`+`
	`5`	`+/**`
	`6`	`+ * Definition for singly-linked list.`
	`7`	`+ * type ListNode struct {`
	`8`	`+ * Val int`
	`9`	`+ * Next *ListNode`
	`10`	`+ * }`
	`11`	`+ */`
	`12`	`+func hasCycle(head *ListNode) bool {`
	`13`	`+ for p1, p2 := head, head; p1 != nil && p2 != nil; p1 = p1.Next {`
	`14`	`+ if p2 = p2.Next; p2 != nil {`
	`15`	`+ if p2 = p2.Next; p1 == p2 {`
	`16`	`+ return true`
	`17`	`+ }`
	`18`	`+ }`
	`19`	`+ }`
	`20`	`+ return false`
	`21`	`+}`

Lines changed: 54 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1 +1,55 @@`
`1`	`1`	`package linked_list_cycle`
	`2`	`+`
	`3`	`+import (`
	`4`	`+ "testing"`
	`5`	`+`
	`6`	`+ . "github.com/openset/leetcode/internal/kit"`
	`7`	`+)`
	`8`	`+`
	`9`	`+type caseType struct {`
	`10`	`+ input []int`
	`11`	`+ pos int`
	`12`	`+ expected bool`
	`13`	`+}`
	`14`	`+`
	`15`	`+func TestHasCycle(t *testing.T) {`
	`16`	`+ tests := [...]caseType{`
	`17`	`+ {`
	`18`	`+ input: []int{3, 2, 0, -4},`
	`19`	`+ pos: 1,`
	`20`	`+ expected: true,`
	`21`	`+ },`
	`22`	`+ {`
	`23`	`+ input: []int{1, 2},`
	`24`	`+ pos: 0,`
	`25`	`+ expected: true,`
	`26`	`+ },`
	`27`	`+ {`
	`28`	`+ input: []int{1, 2, 3, 4, 5},`
	`29`	`+ pos: -1,`
	`30`	`+ expected: false,`
	`31`	`+ },`
	`32`	`+ {`
	`33`	`+ input: []int{1},`
	`34`	`+ pos: -1,`
	`35`	`+ expected: false,`
	`36`	`+ },`
	`37`	`+ }`
	`38`	`+ for _, tc := range tests {`
	`39`	`+ input := SliceInt2ListNode(tc.input)`
	`40`	`+ p, curr := input, input`
	`41`	`+ for i := 0; curr != nil && tc.pos >= 0; i, curr = i+1, curr.Next {`
	`42`	`+ if i == tc.pos {`
	`43`	`+ p = curr`
	`44`	`+ }`
	`45`	`+ if curr.Next == nil {`
	`46`	`+ curr.Next = p`
	`47`	`+ break`
	`48`	`+ }`
	`49`	`+ }`
	`50`	`+ output := hasCycle(input)`
	`51`	`+ if output != tc.expected {`
	`52`	`+ t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)`
	`53`	`+ }`
	`54`	`+ }`
	`55`	`+}`

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