Commit337e300

whoisnp

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abranhe

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added is_palindrome

1 parentebd5e43 commit337e300Copy full SHA for 337e300

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data-structures/linked-lists
- is_palindrome.py

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`‎data-structures/linked-lists/is_palindrome.py‎`

Lines changed: 72 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,72 @@`
	`1`	`+defis_palindrome(head):`
	`2`	`+ifnothead:`
	`3`	`+returnTrue`
	`4`	`+fast,slow=head.next,head`
	`5`	`+whilefastandfast.next:`
	`6`	`+fast=fast.next.next`
	`7`	`+slow=slow.next`
	`8`	`+second=slow.next`
	`9`	`+node=None`
	`10`	`+whilesecond:`
	`11`	`+nxt=second.next`
	`12`	`+second.next=node`
	`13`	`+node=second`
	`14`	`+second=nxt`
	`15`	`+whilenode:`
	`16`	`+ifnode.val!=head.val:`
	`17`	`+returnFalse`
	`18`	`+node=node.next`
	`19`	`+head=head.next`
	`20`	`+returnTrue`
	`21`	`+`
	`22`	`+`
	`23`	`+defis_palindrome_stack(head):`
	`24`	`+ifnotheadornothead.next:`
	`25`	`+returnTrue`
	`26`	`+`
	`27`	`+# Get the midpoint`
	`28`	`+slow=fast=cur=head`
	`29`	`+whilefastandfast.next:`
	`30`	`+fast,slow=fast.next.next,slow.next`
	`31`	`+`
	`32`	`+# Push the second half into the stack`
	`33`	`+stack= [slow.val]`
	`34`	`+whileslow.next:`
	`35`	`+slow=slow.next`
	`36`	`+stack.append(slow.val)`
	`37`	`+`
	`38`	`+# Comparison`
	`39`	`+whilestack:`
	`40`	`+ifstack.pop()!=cur.val:`
	`41`	`+returnFalse`
	`42`	`+cur=cur.next`
	`43`	`+`
	`44`	`+returnTrue`
	`45`	`+`
	`46`	`+`
	`47`	`+defis_palindrome_dict(head):`
	`48`	`+ifnotheadornothead.next:`
	`49`	`+returnTrue`
	`50`	`+d= {}`
	`51`	`+pos=0`
	`52`	`+whilehead:`
	`53`	`+ifhead.valind.keys():`
	`54`	`+d[head.val].append(pos)`
	`55`	`+else:`
	`56`	`+d[head.val]= [pos]`
	`57`	`+head=head.next`
	`58`	`+pos+=1`
	`59`	`+checksum=pos-1`
	`60`	`+middle=0`
	`61`	`+forvind.values():`
	`62`	`+iflen(v)%2!=0:`
	`63`	`+middle+=1`
	`64`	`+else:`
	`65`	`+step=0`
	`66`	`+foriinrange(0,len(v)):`
	`67`	`+ifv[i]+v[len(v)-1-step]!=checksum:`
	`68`	`+returnFalse`
	`69`	`+step+=1`
	`70`	`+ifmiddle>1:`
	`71`	`+returnFalse`
	`72`	`+returnTrue`

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Commit337e300

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`‎data-structures/linked-lists/is_palindrome.py‎`

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