求加分，纯手打啊有木有……
public class Test {
/*
*
* 警察局抓住了A、B、C、D四名盗窃嫌疑犯，
* 其中只有一人是小偷。在审问时，A说：“我
* 不是小偷”；B说：“C是小偷”；C说：“小偷
* 肯定是D”；D说：“C在冤枉好人”。现在已经
* 知道这四人中有三人说的是真话，一人说的
* 是假话。请问到底谁是小偷？
*
* 即A说：thief ！= A;
* B说：thief == C;
* C说：thief == D;
* D说：thief ！= D;
*
* 先分别假设他们都是小偷，如果这个条件导致
* 四个人有三个说的是真话，一个人是假话
* 即abcd四人说的条件有三个成立，一个不
* 成立即为真相！
*/
public static void main(String[] args) {
char thief;//这个人是小偷
//abcd分别代表真假，0为假，1为真，count为条件成立的个数，count=3说明有是3个说的是真话，1个是假话
int a,b,c,d,count;
for(thief='A';thief<='D';thief++){//先假设小偷是A,然后循环假设
a=thief!='A'?1:0;
b=thief=='C'?1:0;
c=thief=='D'?1:0;
d=thief!='D'?1:0;
count=a+b+c+d;
if(count==3){
System.out.println("真正的小偷是"+thief);
}
}
}
}
❷ Java 穷举问题
没有什么是绝对的,什么叫这个问题没人会解决的?
这个我正好有相应的解法,等一下贴出来:
//不用穷举法,用递归
public class InnerLoops {
public static void main(String[] args) {
String a = "0123456789";//可变
int rows = 3;//可变
char[][] c = new char[rows][];
for(int i=0; i<rows; i++)
c[i]=a.toCharArray();
inner(c,0,0);
}
public static final void inner(char[][] array,int currentRow,int currentColumn){
if(currentColumn<array[currentRow].length){
if(currentRow==array.length-1){
print(array);
}
if(hasNext(array,currentRow)){
inner(array,currentRow+1,0);
}
ring(array,currentRow);
inner(array,currentRow,currentColumn+1);
}
}
private static final boolean hasNext(char[][] array, int row) {
return array.length>row+1;
}
private static final void print(char[][] array) {
System.out.println(toString(array));
}
private static final String toString(char[][] array) {
String s = "";
for(int i=0; i<array.length; i++)
s+=(array[i][0]);
return s;
}
//使row行上的数往前推一位,溢出的0位补到最后一位
private static final void ring(char[][] array, int row) {
char t = array[row][0];
for(int i=1; i<array[row].length; i++)
array[row][i-1]=array[row][i];
array[row][array[row].length-1]=t;
}
}
❸ 急！！在线等！JAVA采用穷举法，对100到999的任意三位数m，首先求其个位、十位、百位，用x y z表示。
x=m/100;
y=m%100/10;
z=m%100%10;
❹ java穷举法给出任一字符串， 如abcdd,找出所有可能的字母组合（如ab ac add dd …… ） 有谢谢！！急！！
public class Zuhe {
public static void Method(String a){
StringBuffer str=new StringBuffer();
int l=a.length();
for(int i=0;i<l;i++){
str.delete(0,str.length());
for(int j=l-i-1;j>-1;j--){
char chh=a.charAt(j);
str.append(chh);
System.out.println(str);
}
}
}
public static void main(String[] args) {
String ssstr="abcd";
Method(ssstr);
}
}
❺ 百钱百鸡(穷举算法)
设公鸡、母鸡、小鸡分别为x、y、z 只，由题意得：
x＋y＋z ＝100……①
5x＋3y＋(1/3)z ＝100……②
有两个方程，三个未知量，称为不定方程组，有多种解。
令②×3－①得：7x＋4y＝100；
即：y ＝(100－7x)/4＝25－(7/4)x
由于y 表示母鸡的只数，它一定是自然数，而4 与7 互质，因此x 必须是4 的倍数。我们把它写成：x=4k（k 是自然数），于是y=25-7k，代入原方程组，可得：z=75+3k。把它们写在一起有：
x ＝4k
y ＝25 - 7k
z ＝75+ 3k
一般情况下，当k 取不同数值时，可得到x、y、z 的许多组值。但针对本题的具体问题，由于x、y、z 都是100 以内的自然数，故k 只能取1、2、3 三个值，这样方程组只有以下三组解：
一、 x ＝4；y ＝18；z ＝78
二、 x ＝8；y ＝11；z ＝81
三、 x ＝12；y ＝4；z ＝84
❻ 请用java中的穷举法判断一个范围内的数是否为素数
b=0是把0赋值给b 相当于b的值是0
b==0是判断b是不是等于0 如果表达式成立则执行{}中的内容否则执行else{}的内容
b=1是把1赋值给b 相当于b的值是1
❼ java穷举搜索法，谁来写个!
算24点
穷举法
solution类
package test;
import java.util.Enumeration;
import java.util.Vector;
public class Solution {
static Vector numbers;
private boolean hasSolution;
private Vector theSolution;
private double theResult;
static final int TOTAL_POSITION = 13;
static final int NUM_POSITION[] = { 1, 4, 8, 11 };
static int numCombin[][] = new int[24][4];
static boolean hasNumCombin = false;
static final int OP_POSITION[] = { 2, 6, 10 };
static int opCombin[][] = new int[64][3];
static boolean hasOpCombin = false;
static Character whiteSpace = new Character(' ');
static Character openParen = new Character('(');
static Character closeParen = new Character(')');
static Character addition = new Character('+');
static Character subtract = new Character('-');
static Character multiply = new Character('*');
static Character division = new Character('/');
static final int PAREN_POSITION[] = { 0, 3, 5, 7, 9, 12 };
static final int PAREN_COMBIN[][] = { { 0, 0, 0, 0, 0, 0 },
{ 1, 0, 2, 0, 0, 0 }, { 1, 0, 0, 0, 2, 0 }, { 0, 1, 0, 0, 2, 0 },
{ 0, 1, 0, 0, 0, 2 }, { 0, 0, 0, 1, 0, 2 }, { 1, 0, 2, 1, 0, 2 } };
public Solution(int num0, int num1, int num2, int num3) {
theSolution = null;
numbers = new Vector(4);
numbers.addElement(new Integer(num0));
numbers.addElement(new Integer(num1));
numbers.addElement(new Integer(num2));
numbers.addElement(new Integer(num3));
searchSolution();
}
public Vector getSolution() {
return theSolution;
}
public boolean hasSolution() {
return hasSolution;
}
private static void numberCombination() {
Vector numbers = new Vector(4);
int count = 0;
if (hasNumCombin)
return;
for (int i = 0; i < 4; i++)
numbers.addElement(new Integer(i));
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 3; j++) {
for (int k = 0; k < 2; k++) {
Vector tmpNumbers = (Vector) numbers.clone();
numCombin[count][0] = ((Integer) tmpNumbers.elementAt(i))
.intValue();
tmpNumbers.removeElementAt(i);
numCombin[count][1] = ((Integer) tmpNumbers.elementAt(j))
.intValue();
tmpNumbers.removeElementAt(j);
numCombin[count][2] = ((Integer) tmpNumbers.elementAt(k))
.intValue();
tmpNumbers.removeElementAt(k);
numCombin[count][3] = ((Integer) tmpNumbers.elementAt(0))
.intValue();
tmpNumbers.removeElementAt(0);
count++;
}
}
}
hasNumCombin = true;
}
private static void operatorCombination() {
int count = 0;
if (hasOpCombin)
return;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
for (int k = 0; k < 4; k++) {
opCombin[count][0] = i;
opCombin[count][1] = j;
opCombin[count][2] = k;
count++;
}
}
}
hasOpCombin = true;
}
private void searchSolution() {
Vector tmpExpression = new Vector(13);
int count = 0;
numberCombination();
operatorCombination();
for (int i = 0; i < 13; i++)
tmpExpression.addElement(whiteSpace);
for (int num = 0; num < 24; num++) {
for (int paren = 0; paren < 7; paren++) {
for (int op = 0; op < 64; op++) {
if (count++ % 500 == 0)
for (int i = 0; i < 4; i++)
tmpExpression.setElementAt(numbers
.elementAt(numCombin[num][i]),
NUM_POSITION[i]);
for (int i = 0; i < 6; i++)
switch (PAREN_COMBIN[paren][i]) {
case 1:
tmpExpression.setElementAt(openParen,
PAREN_POSITION[i]);
break;
case 2:
tmpExpression.setElementAt(closeParen,
PAREN_POSITION[i]);
break;
case 0:
tmpExpression.setElementAt(whiteSpace,
PAREN_POSITION[i]);
break;
}
for (int i = 0; i < 3; i++)
switch (opCombin[op][i]) {
case 0:
tmpExpression
.setElementAt(addition, OP_POSITION[i]);
break;
case 1:
tmpExpression
.setElementAt(subtract, OP_POSITION[i]);
break;
case 2:
tmpExpression
.setElementAt(multiply, OP_POSITION[i]);
break;
case 3:
tmpExpression
.setElementAt(division, OP_POSITION[i]);
break;
}
try {
theResult = (new Expression(tmpExpression)).getValue();
} catch (IllegalExpressionException e) {
continue;
}
if (theResult == 24D) {
hasSolution = true;
theSolution = tmpExpression;
return;
}
}
}
}
hasSolution = false;
theSolution = null;
}
public static void printSolution(Vector theSolution) {
for (Enumeration e = theSolution.elements(); e.hasMoreElements();) {
System.out.print(e.nextElement());
}
}
public static void main(String[] args) {
Solution solution = new Solution(5, 7, 8, 9);
if (solution.hasSolution) {
printSolution(solution.getSolution());
}
}
}
IllegalExpressionException类
package test;
public class IllegalExpressionException extends Exception {
public IllegalExpressionException() {
}
public IllegalExpressionException(String msg) {
super(msg);
}
}
Expression类
package test;
import java.util.*;
public class Expression {
protected String inputExpression;
private Stack operatorStack;
private Stack postFixStack;
private final int EOL = 0;
private final int VALUE = 1;
private final int OPAREN = 2;
private final int CPAREN = 3;
private final int MULT = 4;
private final int DIV = 5;
private final int PLUS = 6;
private final int MINUS = 7;
private final int INPUT_PRECEDENCE[] = { 0, 0, 100, 0, 3, 3, 1, 1 };
private final int STACK_PRECEDENCE[] = { -1, 0, 0, 99, 4, 4, 2, 2 };
private double currentValue;
private double theResult;
private int lastToken;
public Expression() {
inputExpression = null;
operatorStack = new Stack();
postFixStack = new Stack();
operatorStack.push(new Integer(0));
}
public Expression(String inString) {
inputExpression = inString.trim();
operatorStack = new Stack();
postFixStack = new Stack();
operatorStack.push(new Integer(0));
}
public Expression(Vector inVector) {
StringBuffer tmpString = new StringBuffer();
for (Enumeration e = inVector.elements(); e.hasMoreElements(); tmpString
.append(e.nextElement()))
;
inputExpression = tmpString.toString().trim();
operatorStack = new Stack();
postFixStack = new Stack();
operatorStack.push(new Integer(0));
}
public void setExpression(String inString) {
inputExpression = inString.trim();
}
public String getExpression() {
return removeSpace(inputExpression);
}
public double getValue() throws IllegalExpressionException {
StringTokenizer parser = new StringTokenizer(inputExpression,
"+-*/() ", true);
do
if (!parser.hasMoreTokens()) {
lastToken = 0;
processToken();
} else {
String token = parser.nextToken();
char firstChar = token.charAt(0);
if (!Character.isWhitespace(firstChar)) {
if (token.length() == 1 && isOperator(firstChar)) {
switch (firstChar) {
case '+':
lastToken = PLUS;
break;
case '-':
lastToken = MINUS;
break;
case '*':
lastToken = MULT;
break;
case '/':
lastToken = DIV;
break;
case '(':
if (lastToken != VALUE)
lastToken = OPAREN;
else
throw new IllegalExpressionException(
"Missing operator");
break;
case ')':
lastToken = CPAREN;
break;
}
} else {
try {
currentValue = Double.valueOf(token).doubleValue();
} catch (NumberFormatException e) {
throw new IllegalExpressionException(
"Unknown symbol");
}
if (lastToken != 1 && lastToken != 3)
lastToken = 1;
else
throw new IllegalExpressionException(
"missing operator");
}
processToken();
}
}
while (lastToken != EOL);
if (postFixStack.empty())
throw new IllegalExpressionException("Missing operand");
theResult = ((Double) postFixStack.pop()).doubleValue();
if (!postFixStack.empty())
throw new IllegalExpressionException("Missing operator");
else
return theResult;
}
private String removeSpace(String inputString) {
StringBuffer s = new StringBuffer();
for (int i = 0; i < inputString.length(); i++) {
char c;
if ((c = inputString.charAt(i)) != ' ')
s.append(inputString.charAt(i));
}
return s.toString();
}
private void processToken() throws IllegalExpressionException {
switch (lastToken) {
case VALUE:
postFixStack.push(new Double(currentValue));
return;
case CPAREN:
int topOperator;
while ((topOperator = ((Integer) operatorStack.peek()).intValue()) != OPAREN
&& topOperator != EOL)
applyOperation(topOperator);
if (topOperator == OPAREN)
operatorStack.pop();
else
throw new IllegalExpressionException("Missing open parenthesis");
break;
default:
while (INPUT_PRECEDENCE[lastToken] <= STACK_PRECEDENCE[topOperator = ((Integer) operatorStack
.peek()).intValue()])
applyOperation(topOperator);
if (lastToken != EOL)
operatorStack.push(new Integer(lastToken));
break;
}
}
private void applyOperation(int topOperator)
throws IllegalExpressionException {
if (topOperator == OPAREN)
throw new IllegalExpressionException("Unbalanced parenthesis");
double rightOperand = getPostStackTop();
double leftOperand = getPostStackTop();
if (topOperator == PLUS)
postFixStack.push(new Double(leftOperand + rightOperand));
else if (topOperator == MINUS)
postFixStack.push(new Double(leftOperand - rightOperand));
else if (topOperator == MULT)
postFixStack.push(new Double(leftOperand * rightOperand));
else if (topOperator == DIV)
if (rightOperand != (double) 0)
postFixStack.push(new Double(leftOperand / rightOperand));
else
throw new IllegalExpressionException("Division by zero");
operatorStack.pop();
}
private double getPostStackTop() throws IllegalExpressionException {
if (postFixStack.empty())
throw new IllegalExpressionException("Missing operand");
else
return ((Double) postFixStack.pop()).doubleValue();
}
private boolean isOperator(char c) {
return c == '+' || c == '-' || c == '*' || c == '/' || c == '('
|| c == ')';
}
}
❽ 编写一个java程序,用穷举法找出2~50之间的素数,并打印出来.
public static void main(String[] args) {
int i, k;
boolean yes;
for (k = 2; k <= 50; k++) {
yes = true;
i = 2;
while (i <= k - 1 && yes) {
if (k % i == 0)
yes = false;
i++;
}
if (yes)
System.out.print(k + " ");
}
}