class Node {
Object item; Node next;
Node (Object v) {
item = v; next = null;
}
}
头指针，½Iºå°¾æŒ‡é’ˆ
åˆå§‹åŒ–：(x¨¬)head = null;
åœ?/SPAN>xåŽæ’å…?/SPAN>tåQ?/SPAN>
if ( x == null)
{ head = t; head.next = null; }
else { t.next = x.next; x.next = t; }
¿U»èµ°x之åŽçš„结点：(x¨¬)t = x.next; x.next = t.next;
循环é历åQ?/SPAN>for ( t = head; t != null; t = t.next )
‹‚€(g¨¨)查链表是å¦äØ“(f¨´)½Iºï¼š(x¨¬)if ( head == null )
½Iºå¤´¾l“点åQŒç©ºž®¾æŒ‡é’?/SPAN>
åˆå§‹åŒ–：(x¨¬)head = new Node(); head.next = null;
åœ?/SPAN>xåŽæ’å…?/SPAN>tåQ?/SPAN>t.next = x.next; x.next = t;
¿U»èµ°x之åŽçš„结点：(x¨¬)t = x.next; x.next = t.next;
循环é历åQ?/SPAN>for ( t = head.next; t != null; t = t.next )
‹‚€(g¨¨)查链表是å¦äØ“(f¨´)½Iºï¼š(x¨¬)if ( head.next == null )
½Iºå¤´¾l“点åQŒç©ºž®„¡»“ç‚?/SPAN>
åˆå§‹åŒ–：(x¨¬)head = new Node(); z = new Node(); head.next = z; z.next = z;
åœ?/SPAN>xåŽæ’å…?/SPAN>tåQ?/SPAN>t.next = x.next; x.next = t;
¿U»èµ°x之åŽçš„结点：(x¨¬)t = x.next; x.next = t.next;
循环é历åQ?/SPAN>for ( t = head.next; t != z; t = t.next )
‹‚€(g¨¨)查链表是å¦äØ“(f¨´)½Iºï¼š(x¨¬)if ( head.next == z )
循环链表
½W¬ä¸€‹Æ¡æ’入：(x¨¬)head.next = head;
åœ?/SPAN>xåŽæ’å…?/SPAN>tåQ?/SPAN>t.next = x.next; x.next = t;
¿U»èµ°x之åŽçš„结点：(x¨¬)t = x.next; x.next = t.next;
循环é历åQ?/SPAN>t = head; do { t = t.next; } while ( t != head );
‹‚€(g¨¨)查是å¦åªæœ‰ä¸€ä¸ªæ•°æ®é¡¹åQ?/SPAN>if ( head.next == head )
å †æ ˆ
数组实现
class Stack {
private Object[] s;
private int n;
Stack ( int maxN ) {
s = new Object[maxN]; n = 0;
}
boolean isEmpty() { return ( n == 0 ); }
void push ( Object item ) { s[n++] = item; }
Object pop() {
Object t = s[--n]; s[n] = null; return t;
}
}
链表实现
class Stack {
private Node head;
private class Node {
Object item; Node next;
Node ( Object item, Node next ) {
this.item = item; this.next = next;
}
}
Stack ( Object maxN ) { head = null; }
boolean isEmpty() { return ( head ==null ); }
void push ( Object item ) { head = new Node(item, head); }
Object pop() {
Object v = head.item;
Node t = head.next;
head = t;
return v;
}
}
FIFO队列的链表实�/SPAN>
class Queue {
private class Node {
Object item; Node next;
Node ( Object item ) {
this.item = item; this.next = null;
}
}
Private Node head, tail;
Queue ( Object max ) { head = null; tail = null; }
boolean isEmpty() { return ( head ==null ); }
void put ( Object item ) {
Node t = tail;
tail = new Node(item);
if ( empty() )
head = tail;
else t.next = tail
}
Object get() {
Object v = head.item;
Node t = head.next;
head = t;
return v;
}
}
Flyingis 2006-02-05 23:08 å‘表评论
]]>½Ž—法作äØ“(f¨´)实现计算机程åºå®žçŽ°æ—¶è§£å†³é—®é¢˜çš„方法，在计½Ž—机应用领域å‘挥ç€ä¸¾èƒöè½»é‡çš„ä½œç”¨ã€‚å®ƒç ”ç©¶çš„å†…å®ÒŽ(gu¨©)˜¯è§£å†³é—®é¢˜çš„方法，而ä¸æ˜¯è®¡½Ž—机½E‹åºçš„本íw«ã€‚一个优¿U€çš„算法å¯ä»¥è¿è¡Œåœ¨æ¯”较慢的计算æœÞZ¸ŠåQŒä½†ä¸€ä¸ªåŠ£è´¨çš„½Ž—法在一å°æ€§èƒ½å¾ˆå¼ºçš„计½Ž—机上也ä¸ä¸€å®šèƒ½æ»¡èƒö应用的需è¦ï¼Œå› æ¤åQŒåœ¨è®¡ç®—机程åºè®¾è®¡ä¸åQŒç®—æ³•è®¾è®¡å¾€å¾€å¤„äºŽæ ¸å¿ƒ(j¨©)åœîC½ã€‚如何去设计一个适åˆç‰¹å®šåº”用的优¿U€½Ž—法是众多开å‘äh员所å…Ïx(ch¨®ng)³¨çš„焦点，在算法设计时åQŒéœ€è¦äº†(ji¨£n)解算法设计的规则ã€?/span>
è¦æƒ³å……分ç†è§£½Ž—法òq¶æœ‰æ•ˆåœ°åº”用于实际问题，关键是对½Ž—法的分æžã€‚通常我们å¯ä»¥åˆ©ç”¨å®žéªŒå¯ÒŽ(gu¨©)¯”分æžã€æ•°å¦æ–¹æ³•æ¥åˆ†æž½Ž—法。实验对比分æžå¾ˆ½Ž€å•ï¼Œä¸¤ä¸ª½Ž—法ç›æ€º’比较åQŒå®ƒä»¬éƒ½èƒ½è§£å†›_Œä¸€é—®é¢˜åQŒåœ¨ç›¸åŒçŽ¯å¢ƒä¸‹ï¼Œå“ªä¸ª½Ž—法的速度快我们一般就ä¼?x¨¬)认ä¸ø™¿™ä¸ªç®—法性能更好。数å¦æ–¹æ³•èƒ½ž®†ç®—法分æžçš„æ›´äØ“(f¨´)¾l†è‡´åQŒèƒ½åœ¨ä¸¥å¯†çš„逻辑推ç†åŸºç¡€ä¸Šåˆ¤æ–算法的优劣åQŒä½†åœ¨å®Œæˆå®žé™…项目过½E‹ä¸åQŒæˆ‘们很多时候都ä¸èƒ½åŽÕdš˜q™ç§ä¸¥å¯†çš„论è¯ä¸ŽæŽ¨æ–åQŒå› 为我们ä¸æ˜¯åœ¨å®Œæˆä¸€é“æ•°å¦éš¾é¢˜ï¼Œä¹Ÿä¸æ˜¯æ•°å¦é¢†åŸŸçš„专家åQŒå°†å¤§é‡çš„时间花费在公å¼çš„计½Ž—与è¯æ˜Žä¸Šä¼š(x¨¬)å¯ÆD‡´æ•´ä¸ª™å¹ç›®˜q›åº¦¾~“æ…¢ã€æˆæœ¬è¿‡é«˜ï¼Œå› æ¤åQŒåœ¨½Ž—法设计ä¸ï¼Œæˆ‘们往往采用能近ä¼ÆD¡¨è¾¾æ€§èƒ½çš„方法æ¥å±•ç¤ºæŸä¸ª½Ž—æ³•çš„æ€§èƒ½æŒ‡æ ‡ã€‚ä¾‹å¦‚ï¼Œè®¡ç®—æœºå¯¹n2å’?/span>n2+2nçš„å“应速度åQŒå½“næ¯”è¾ƒå¤§çš„æ—¶å€™å‡ ä¹Žä¸€æ äh²¡ä»€ä¹ˆåŒºåˆ«ï¼Œæˆ‘们便å¯ç›´æŽ¥è®¤äØ“(f¨´)åŽè€…算法的å¤æ‚度äØ“(f¨´)n2。在分枽Ž—法æ—Óž¼Œéšè—¾l†èŠ‚çš„æ•°å¦è¡¨½Cºæ³•æˆäØ“(f¨´)大O记法åQŒå®ƒå¯ä»¥å¸®åŠ©æˆ‘们½Ž€åŒ–算法å¤æ‚度的许多细节，æå–主è¦æˆåˆ†åQŒè¿™å’Œé¥æ„Ÿå›¾åƒå¤„ç†ä¸çš„主æˆåˆ†åˆ†æžæ€æƒ³ç›¸è¿‘ã€?/span>
åŸÞZºŽ½Ž—法å¤æ‚度简化表辄¡š„æ€æƒ³åŸºç¡€ä¸Šï¼Œæˆ‘们通常ä¼?x¨¬)对½Ž—法˜q›è¡Œæœ€å情况分æžå’Œòq›_‡æƒ…况分æžã€‚对于一个给定的½Ž—法åQŒå¦‚果能ä¿è¯å®ƒçš„最å情况下的性能ä¾ç„¶ä¸é”™å½“然很好åQŒä½†æ˜¯åœ¨æŸäº›æƒ…况下，½E‹åºçš„最å情å†ëŠ®—法的˜q行旉™—´å’Œå®žé™…情å†ëŠš„˜q行旉™—´ç›¸å·®å¾ˆå¤§åQŒåœ¨å®žé™…应用ä¸æˆ‘ä»¬å‡ ä¹Žä¸ä¼?x¨¬)碰到最å情况下的输入，那么æ¤æ—¶˜q›è¡Œæœ€å情况分æžæ˜¾å¾—有些画蛇添‘»I¼Œç‰¹åˆ«æ˜¯åˆ†æžæœ€å情å†ëŠ®—法会(x¨¬)èŠÞp´¹å¤§é‡¾_‘ÖŠ›çš„时候。算法的òq›_‡æƒ…况分æžå¯ä»¥å¸®åŠ©æˆ‘们估计½E‹åºçš„性能åQŒä½œä¸ºç®—法分æžçš„åŸºæœ¬æŒ‡æ ‡ä¹‹ä¸€åQŒä½†æ˜¯åã^å‡æƒ…况和实际情况ä»ç„¶ä¼?x¨¬)有相差很大的时候，˜q™æ—¶æˆ‘们便å¯ä»¥ä‹É用éšæœºæ³•æ¥å°½é‡æ¨¡æ‹ŸçŽ°å®žä¸çš„情况，˜q™æ ·å¯ä»¥å¾—åˆ°åœ¨ä¸¥æ ¼çš„æ¦‚çŽ‡æ„义上的预测˜q行旉™—´ã€‚å¦å¤–，对于一个ç»å…¸ç®—法，我们没有必è¦å†åŽ»å¯¹è¯¥½Ž—法˜q›è¡Œæ”¹è¿›åQŒç ”½I¶å®ƒçš„上界和下界åQŒåªéœ€è¦äº†(ji¨£n)解该½Ž—法的特性，然åŽåœ¨åˆé€‚的时候ä‹É用它ã€?/span>
最åŽï¼Œå½“一个程åºå˜å¿«å’Œå˜æ…¢åQŒè®©è®¡ç®—机åæ˜ å‡ºæ¥çš„æ—‰™—´å·®å‡ 乎ä¸ä¼?x¨¬)让äºÞZñ”生感觉的时候，我们也没有必è¦åŽ»æ”¹è¿›˜q™ä¸ª½Ž—法åQŒä¾‹å¦‚程åºè¿›è¡?/span>1000‹Æ¡åó@环花è´?/span>0.001¿U’，改进åŽäØ“(f¨´)0.1¿U’，在实际应用ä¸é€šå¸¸ä¹Ÿåªéœ€è¦å‡ åƒæ¬¡å¾ªçŽ¯åQŒæ¤æ—¶æˆ‘们就没有必è¦åŽ»èŠ±æ—‰™—´æ¥ç ”½I¶è¿™ä¸ªç®—法了(ji¨£n)åQŒåªè¦è¯¥½Ž—法能棼‹®å®Œæˆä“Q务å³å¯ã€?/span>
Flyingis 2006-01-22 00:34 å‘表评论
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