表達(dá)式求值 數(shù)據(jù)結(jié)構(gòu) java實(shí)現(xiàn)

1. 定義優(yōu)先級(jí)和優(yōu)先級(jí)表

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Java代碼

/**

* 運(yùn)算符優(yōu)先權(quán)

*/

public enum Precede {

/**

* 優(yōu)先權(quán)高

*/

LARGER,

/**

* 優(yōu)先權(quán)低

*/

LESS;

/**

* 優(yōu)先級(jí)表

* + - * /

* +

* -

* *

* /

*/

private static Precede[][] precedes = new Precede[4][4];

static {

// 根據(jù)優(yōu)先級(jí)表初始化precedes數(shù)組

for (int i = 0; i precedes.length; i++) {

for (int j = 0; j precedes[i].length; j++) {

if ((i == 0 || i == 1) j 1) {

precedes[i][j] = LESS;

} else {

precedes[i][j] = LARGER;

}

}

}

}

/**

* 判斷2個(gè)運(yùn)算符的優(yōu)先級(jí)

*/

public static Precede judgePrecede(char operand1, char operand2) {

int left = getIndex(operand1);

int right = getIndex(operand2);

return precedes[left][right];

}

/**

* 獲取運(yùn)算符對(duì)應(yīng)的數(shù)組索引

*/

private static int getIndex(char operand) {

switch (operand) {

case '+':

return 0;

case '-':

return 1;

case '*':

return 2;

case '/':

return 3;

default:

throw new IllegalArgumentException();

}

}

}

2. 表達(dá)式求值

Java代碼

/**

* 整數(shù)表達(dá)式運(yùn)算

*/

public class EvaluateExpression {

/**

* 表達(dá)式

*/

private String expression;

/**

* 最初的表達(dá)式

*/

private String initExpression;

/**

* 運(yùn)算符棧

*/

private MyStackCharacter optr = new MyArrayStackCharacter();

/**

* 操作數(shù)棧

*/

private MyStackInteger opnd = new MyArrayStackInteger();

/**

* 表明下一個(gè)是否應(yīng)該是數(shù)字

*/

private boolean numberNext;

public EvaluateExpression(String expression) {

this.expression = expression;

this.initExpression = expression;

numberNext = true;

}

/**

* 求值

*/

public Integer evaluate() {

delBlank();

handleParentheses();

while (true) {

if ("".equals(expression)) {

break;

}

if (expression.matches("^-?\\d+.*$") numberNext) {

opnd.push(getInteger());

continue;

} else {

Character operand = expression.charAt(0);

numberNext = true;

expression = expression.substring(1);

Character pop = optr.pop();

if (pop == null) {

optr.push(operand);

continue;

} else {

Precede precede = Precede.judgePrecede(pop, operand);

switch (precede) {

// 優(yōu)先級(jí)高時(shí)運(yùn)算前2個(gè)操作數(shù)

case LARGER: {

optr.push(operand);

Integer next = opnd.pop();

Integer last = opnd.pop();

evaluateNow(last, pop, next);

break;

}

// 優(yōu)先級(jí)低時(shí)運(yùn)算前一個(gè)操作數(shù)和后一個(gè)操作數(shù)

case LESS: {

optr.push(pop);

Integer last = opnd.pop();

Integer next = getInteger();

evaluateNow(last, operand, next);

break;

}

}

}

}

}

// 運(yùn)算結(jié)果

Integer result = null;

if (optr.length() == 0 opnd.length() == 1) {

result = opnd.pop();

} else if (optr.length() == 1 opnd.length() == 2) {

Integer next = opnd.pop();

Integer last = opnd.pop();

evaluateNow(last, optr.pop(), next);

result = opnd.pop();

} else {

throw new RuntimeException();

}

return result;

}

/**

* 進(jìn)行實(shí)際的運(yùn)算，并將結(jié)果入棧

*/

private void evaluateNow(Integer last, Character operand, Integer next) {

switch (operand) {

case '+':

opnd.push(last + next);

break;

case '-':

opnd.push(last - next);

break;

case '*':

opnd.push(last * next);

break;

case '/':

opnd.push(last / next);

break;

}

}

/**

* 獲得表達(dá)式開頭部分的整數(shù)

*/

private Integer getInteger() {

StringBuilder sb = new StringBuilder();

int count = 0; // 整數(shù)位

boolean lessZero = false; // 是否是負(fù)數(shù)

if (expression.startsWith("-")) {

sb.append("-");

count++;

lessZero = true;

}

int i = (lessZero ? 1 : 0);

for (; i expression.length(); i++) {

char c = expression.charAt(i);

if (c = '0' c = '9') {

sb.append(c);

count++;

} else {

break;

}

}

expression = expression.substring(count);

numberNext = false;

return Integer.valueOf(sb.toString());

}

/**

* 處理括號(hào). 將括號(hào)內(nèi)的字符串作為子表達(dá)式計(jì)算.

*/

private void handleParentheses() {

while (expression.contains("(")) {

// 左括號(hào)的索引

int left = 0;

// 右括號(hào)的索引

int right = 0;

// 左括號(hào)的數(shù)量

int count = 0;

// 求出左括號(hào)索引

left = expression.indexOf('(');

// 求出對(duì)應(yīng)的右括號(hào)索引

for (int i = left; i expression.length(); i++) {

char c = expression.charAt(i);

if (c == ')') {

count--;

// count為0時(shí)才是對(duì)應(yīng)的右括號(hào)

if (count == 0) {

right = i;

break;

}

} else if (c == '(') {

count++;

} else {

continue;

}

}

// 左右括號(hào)之間是一個(gè)子表達(dá)式, 計(jì)算子表達(dá)式的值，并根據(jù)結(jié)果構(gòu)造出新的表達(dá)式

EvaluateExpression evaluateExpression = new EvaluateExpression(expression.substring(left + 1, right));

expression = expression.substring(0, left) + evaluateExpression.evaluate()

+ expression.substring(right + 1);

}

}

/**

* 刪除表達(dá)式中的空白字符

*/

private void delBlank() {

expression = expression.replaceAll("\\s", "");

}

@Override

public String toString() {

return initExpression;

}

}

3. 進(jìn)行測(cè)試

Java代碼

@Test

public void testEvaluate() {

EvaluateExpression expression = new EvaluateExpression("1 + 2 ");

System.out.println(expression + " = " + expression.evaluate());

expression = new EvaluateExpression("4 + 2 * 3 - 10 / 5");

System.out.println(expression + " = " + expression.evaluate());

expression = new EvaluateExpression("(1+2) * (4 + 5) - (9 / 7)");

System.out.println(expression + " = " + expression.evaluate());

expression = new EvaluateExpression("(1 + (3 * (4 - 9)))");

System.out.println(expression + " = " + expression.evaluate());

expression = new EvaluateExpression("(1 + (3 * (4 - 9))) + (3 * (2 + 3))");

System.out.println(expression + " = " + expression.evaluate());

}

測(cè)試的結(jié)果為:

1 + 2 = 3

4 + 2 * 3 - 10 / 5 = 8

(1+2) * (4 + 5) - (9 / 7) = 26

(1 + (3 * (4 - 9))) = -14

(1 + (3 * (4 - 9))) + (3 * (2 + 3)) = 1

用java實(shí)現(xiàn)一個(gè)數(shù)據(jù)結(jié)構(gòu)！

import java.io.IOException;

import java.util.Scanner;

public class LinkList {

private static Scanner san = new Scanner(System.in);

public static void main(String[] args) throws IOException {

List list = new List();

for (int i = 1; i = 10; i++) {

System.out.print("請(qǐng)輸入第" + i + "個(gè)數(shù): ");

list.add(san.nextInt());

list.print();

}

System.out.println("輸入的數(shù)據(jù)如下: ");

list.print();

}

}

class node {

int data;

node next = this; // 指向自己

}

class List {

private node header = new node();

// 循環(huán)鏈表的尾部添加數(shù)據(jù)

public node add(int data) {

node current = new node();

node temp = header;

while (temp.next != header)

temp = temp.next;

current.data = data;

current.next = temp.next;

temp.next = current;

return current;

}

// 查詢某個(gè)數(shù)字的位置 如果不在 返回-1；

public int search(int data) {

node temp = header;

int n = 0;

while (temp.next != header) {

temp = temp.next;

n++;

if (temp.data == data)

break;

}

if (temp.data == data)

return n;

else

return -1;

}

// 打印出整個(gè)鏈表

public void print() {

node temp = header;

while (temp.next != header) {

temp = temp.next;

System.out.print(temp.data + " ");

}

System.out.println();

}

// 插入數(shù)據(jù)

public node Insert(int pos, int data) {

node temp = header;

node current = new node();

for (int i = 0; i pos - 1; i++) {

if (temp.next != header) {

temp = temp.next;

} else

return null;

}

current.data = data;

if (temp.next != header) {

current.next = temp.next;

}

temp.next = current;

return current;

}

// 刪除某個(gè)數(shù)據(jù)

public node del(int data) {

node temp = header;

node oldtemp = null;

node current = null;

while (temp.next != header) {

oldtemp = temp;

temp = temp.next;

if (temp.data == data) {

current = temp;

break;

}

}

if (current == header)

return null;

oldtemp.next = current.next;

return current;

}

}

用Java語言編寫數(shù)據(jù)結(jié)構(gòu)中順序表的插入刪除查找代碼并實(shí)現(xiàn)

public class Test {

public static void main(String[] args) {

int length = 5;

int ai = 1;

String data = "data";

String[] array = insertArrar(data, ai, length);

data = delArray(array, ai, length);

System.out.println(data);

}

public static String[] insertArrar(String data,int ai,int length){

String[] array = new String[length];

array[ai] = data;

return array;

}

public static String delArray(String[] array,int ai,int length){

String data = "";

data=array[ai];

array[ai]=null;

for(int i = 0; iarray.length;i++){

System.out.println(array[i]);

}

return data;

}

}

數(shù)據(jù)結(jié)構(gòu)在java里如何實(shí)現(xiàn)?

首先Java沒有指針(為了安全和方便編程).

其次數(shù)據(jù)結(jié)構(gòu)和指針無關(guān)，和語言也無關(guān).

Java封裝好了各種基本的數(shù)據(jù)結(jié)構(gòu) 比如:

數(shù)組,隊(duì)列,Stack,HashTable,HashSet,HaspMap等等

你說的順序表 Java中你可以用:

ArrayList 這個(gè)類:

例子:

如果你自己想用Java裸寫一個(gè)類似功能的類可以參考這個(gè):

網(wǎng)頁題目：java數(shù)據(jù)結(jié)構(gòu)代碼實(shí)現(xiàn),數(shù)據(jù)結(jié)構(gòu) java版
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