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[Powered by Google Translate] [Ciú]

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[Chris Gerber, Ollscoil Harvard]

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Is é seo an CS50, CS50.TV]

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Is é ceann úsáideach sonraí struchtúr a stóráil bailiúchán ordú na n-eilimintí scuaine.

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Tá sé in úsáid nuair is gá na heilimintí a bhaint

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san ord céanna mar a cuireadh iad.

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Tá an coincheap ar a dtugtar FIFO, a bhfuil an acrainm do chéad, an chéad amach.

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Chun cabhrú visualize seo, d'fhéadfadh sé a bheith úsáideach pictiúr

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líne Seiceáil ag siopa.

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Mar a thagann daoine, fanacht siad ar chúl an líne.

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An Cashier Bíonn ansin casadh ag freastal ar na custaiméirí ag an tosaigh,

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a scoir an líne amháin ag an am.

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I eolaíocht ríomhaireachta, a tharchur muid go dtí an os comhair an scuaine mar an ceann

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agus ar chúl an eireaball.

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Sampla de nuair a d'fhéadfadh muid seo a úsáid in iarratas

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Is waitlist do rollú rang.

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Mar a bheith suíocháin atá ar fáil sa rang,

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bhfuil an duine ag ceann an liosta feithimh an deis a chlárú sa rang.

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>> Is féidir le scuaine a thógáil ag baint úsáide as aon bhailiúchán

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go bhfuil na sonraí siopaí in ord, ar nós mar eagar nó liosta nasctha.

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Chomh maith leis an mbailiúchán a stóráil na míreanna sa scuaine,

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ní mór dúinn chomh maith le modh chun míreanna a chur ag deireadh na scuaine,

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ar a dtugtar enqueuing,

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agus ceann eile a bhaint mír as an barr an chuí,

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ar a dtugtar dequeuing.

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Is minic gur úsáideach a chur san áireamh ar mhodh eile chun filleadh ar an fad atá ann faoi láthair ar an scuaine

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chomh maith le modh a sheiceáil má tá an scuaine folamh.

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A ligean ar breathnú ar conas a d'fhéadfadh muid a chur i bhfeidhm scuaine na slánuimhreacha i C,

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úsáid a bhaint as le sraith maidir le bailiú na n-eilimintí.

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An chéad, a chruthú dúinn struchtúr a dtugtar scuaine de bheith i seilbh ár n-athróg.

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Bainfimid úsáid as seasta-mhéid sraith innéacs 0 na slánuimhreacha

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a stóráil na heilimintí sin.

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Cuirfimid san áireamh freisin ceann athróg ar a dtugtar

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go siopaí an t-innéacs na dúile atá faoi láthair ag ceann na scuaine.

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A athróg an tríú, ar a dtugtar fad a bheidh, a úsáid

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súil a choinneáil ar líon na n-eilimintí sa eagar.

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Mar mhalairt, d'fhéadfaí tú a mheas ag baint úsáide as eireaball athróg ar a dtugtar

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a chur in iúl an ghné réimse deireanach sa eagar.

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Sula muid ag scríobh cód ar bith níos mó,

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a ligean ar triail a bhaint as ár dearadh.

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Let tús le sraith folamh ar fad 0,

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le leagtar an ceann 0.

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Anois enqueue ligean ar 4 luachanna - 6, 2, 3, agus 1.

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Beidh an fad anois 4,

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agus beidh an ceann fanacht ag 0.

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>> Cad a tharlaíonn má dequeue againn luach?

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Déanfaimid an fad a laghdú go 3,

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an ceann atá leagtha go 1,

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agus seol ar ais an luach 6.

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D'fhéadfadh an cód breathnú mar seo.

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Anseo ní mór dúinn an fheidhm dequeue,

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a thógann pointeoir leis an scuaine - q - agus pointeoir leis an eilimint,

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atá ina slánuimhir chineál.

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An Chéad muid ag seiceáil an fad an scuaine a dhéanamh cinnte tá sé níos mó ná 0,

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chun a chinntiú go bhfuil gné a dequeued.

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Ansin muid ag breathnú ar an raon gnéithe, ag ceann seasamh,

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agus leag an luach eilimint a bheith ar an luach ag an suíomh.

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Ansin linn a athrú an ceann a bheith ar an innéacs seo chugainn

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% An cumas.

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Táimid ag laghdú ansin an fad an scuaine ag 1.

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Mar fhocal scoir, ar ais dúinn fíor a chur in iúl go raibh an dequeue rathúil.

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Má dequeue againn arís, beidh an fad 2,

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Beidh an ceann freisin bheith 2,

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agus beidh an luach ar ais 2.

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>> Cad a tharlaíonn má enqueue eile againn luach den sórt sin mar 7?

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Mar a bhí againn ag deireadh na scuaine,

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ní mór dúinn a wrap thart agus a stóráil ar an luach i 0 eilimint den eagar.

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Mathematically, is féidir é seo a léiriú tríd an fad

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chun an t-innéacs an ceann

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a chomhlíonadh agus a modulus baint úsáide as an acmhainn scuaine.

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Seo go 2 +2, a bhfuil 4% 4,

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bhfuil 0.

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Aistriúchán an smaoineamh seo chun cód ní mór dúinn an fheidhm seo.

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Anseo feicimid an fheidhm enqueue,

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a thógann pointeoir leis an scuaine - q -

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agus tógann sé an eilimint atá le enqueued, atá ina slánuimhir.

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Táimid ag seiceáil eile a dhéanamh cinnte go bhfuil an cumas an scuaine

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tá sé fós níos mó ná an fad atá ann faoi láthair na scuaine.

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Next, a stóráil againn ar an eilimint sa eagar gnéithe

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ag an innéacs atá arna chinneadh ag an ceann +% fad cumas an scuaine.

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Táimid ag méadú ansin an fad scuaine ag 1,

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agus seol ar ais ansin fíor a chur in iúl go raibh an fheidhm enqueue rathúil.

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>> Chomh maith leis an dá fheidhm atá againn atá luaite,

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tá dhá feidhmeanna breise.

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Is é an chéad fheidhm isempty,

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a thógann pointeoir leis an scuaine

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agus fíoraíonn go bhfuil an fad 0.

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Is é an dara feidhm fad,

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a thógann freisin pointeoir leis an scuaine

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agus tuairisceáin an fad atá ann faoi láthair ó na struct.

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Tá an forbhreathnú gearr léirithe amháin i bhfeidhm d'fhéadfadh a scuaine.

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Ceann de na teorainneacha a ghabhann leis an cur i bhfeidhm

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é go bhfuil an scuaine méid uasta socraithe.

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Má iarracht muid a chur gnéithe níos mó ná is féidir leis an scuaine a shealbhú,

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is féidir linn a neamhaird a dhéanamh leis an iarraidh agus an eilimint titim,

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nó is féidir linn a fearr a thabhairt ar ais roinnt de chineál earráide.

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Ag baint úsáide as liosta nasctha seachas eagar

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Bheadh ​​sé níos éasca le méid dinimiciúil an scuaine.

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Mar sin féin, ós rud é nach bhfuil againn rochtain dhíreach ar na gnéithe de liosta nasctha,

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más rud é nach bhfuil muid ag súil a choinneáil ar an eireaball,

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ba mhaith linn a scanadh ar an liosta iomlán nasctha a fháil chun an deireadh gach uair.

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D'fhéadfadh muid a mheas freisin ag baint úsáide as le sraith de chineál eile sonraí,

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mar shampla structs, a chruthú scuainí na n-eilimintí níos casta.

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Ag smaoineamh ar ais go dtí ár sampla de waitlist ranga,

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D'fhéadfadh na struchtúir seo ar son an mhic léinn aonair.

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>> Is é mo ainm Chris Gerber, agus tá sé seo CS50.

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[CS50.TV]

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Agus tuairisceáin - >> amháin níos mó ama.

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Agus seol ar ais fíor chun a léiriú go - an scuaine a bhí rathúil.

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-% An cumas na scuaine -

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Tá sé seo ag dul a bheith spraoi i edit. [Gáire]