青蛙过河问题！注释写的不咋地，有错误。希望大神解释这个程序的rollback()和record（）方法怎么算的？
package com.demo.hwj.javademo.kotlin;
import java.util.Arrays;//要使用工具类；
public class Testing {
static int[] mInput = {1, 2, 3, 0, 9, 10, 11};//这是之前的顺序；这里静态的作用便是方便之后复制；
static int[] mStep = new int[100];//步数
static int[] mResult = {9, 10, 11, 0, 1, 2, 3};//这是之后的顺序
static int mBridgeIndex = 0;//中间的坐标
static int[] mLeft = null;//左边操作的数组
static int[] mRight = null;//右边操作的数组
static int stepPosition = 0;//当前步的坐标
public static void main(String[] args) {
init();//初始化
start();//开始
}
private static void start() {
do {
switch (mStep[stepPosition]) {
case 1:
if (move(1, 1)) {
break;
}
case 2:
if (move(1, 2)) {
break;
}
case 3:
if (move(2, 1)) {
break;
}
case 4:
if (!move(2, 2)) {
//reset mInput ,rollback mStep
rollback();
continue;
}
}
stepPosition++;
} while (!Arrays.equals(mResult, mInput));
outputStep();
}
//这个方法就是输出运动的实况吧；
private static void outputStep() {
int[] finallyStep = Arrays.copyOf(mStep, stepPosition);
reset();//
for (int i = 0; i < finallyStep.length; i++) {
switch (finallyStep[i]) {
case 1:
moveLeft(1);
System.out.printf(i + ": Left walking =>" + Arrays.toString(mInput) + "\n");
break;
case 2:
moveLeft(2);
System.out.printf(i + ": Left jumping =>" + Arrays.toString(mInput) + "\n");
break;
case 3:
moveRight(1);
System.out.printf(i + ": Right walking =>" + Arrays.toString(mInput) + "\n");
break;
case 4:
moveRight(2);
System.out.printf(i + ": Right jumping =>" + Arrays.toString(mInput) + "\n");
break;
}
}
}
//这是初始化，初始化游戏的；
private static void init() {
mBridgeIndex = mInput.length / 2;// get middle bridge's position，用来获取中间的坐标；
mLeft = Arrays.copyOfRange(mInput, 0, mBridgeIndex);//将左边的数组用Arrays工具类的copy of range()方法将从0到中间复制到新数组中；
mRight = Arrays.copyOfRange(mInput, mBridgeIndex + 1, mInput.length);//同左；
Arrays.fill(mStep, 1);//将Setp数组用1填充；
}
/**
* move input child element .include all the way for move
*
* @param direction the direction for move. 1 means left,2 means right
* @param stepInterval the way for move. 1 means walking,2 means jumping
*/
//这是运动的总类，包含了所有的移动方式；
private static boolean move(final int direction, final int stepInterval) {
//这里主要是发现是否有异常；
if (stepInterval != 1 && stepInterval != 2)
new IllegalArgumentException(" stepInterval must equal 1 or 2. -----> line 65");
if (direction != 1 && direction != 2)
new IllegalArgumentException(" direction must equal 1 or 2.-----> line 65");
boolean isWalking;
//这里要判断移动的方式，有跳和走，有左有右
if (direction == 1) {
isWalking = moveLeft(stepInterval);
} else {
isWalking = moveRight(stepInterval);
}
//当被指向时候进行判断；
if (isWalking) {
//record down step
record(direction, stepInterval);
}
return isWalking;
}
private static void record(int direction, int step) {
switch (direction) {
case 1:
mStep[stepPosition] = direction * step;
break;
case 2:
mStep[stepPosition] = direction + step;
break;
}
}
private static void rollback() {
if (mStep[stepPosition] >= 4) {
mStep[stepPosition] = 1;
stepPosition--;
}
if (stepPosition < 0)
stepPosition = 0;
if (mStep[stepPosition] < 4) {
mStep[stepPosition]++;
reset();
}
}
/**
* move input child element .include the way for move is Left
*
* @param stepInterval the way for move. 1 means walking,2 means jumping
* @return if return false that means cannot moving
*/
//左向的方法
private static boolean moveLeft(final int stepInterval) {
for (int i = 0; i < mInput.length; i++) {
if (containOf(mLeft, mInput[i])) {// search item whether inside for mInput
if (i < mInput.length - stepInterval && mInput[i + stepInterval] == 0) {
//change item
int a = mInput[i];
mInput[i + stepInterval] = a;
mInput[i] = 0;
return true;
}
}
}
return false;
}
//右向的方法
private static boolean moveRight(final int stepInterval) {
for (int i = mInput.length - 1; i >= 0; i--) {
if (containOf(mRight, mInput[i])) {// search item whether inside for mInput
if (i >= 0 + stepInterval && mInput[i - stepInterval] == 0) {
//change item
mInput[i - stepInterval] = mInput[i];
mInput[i] = 0;
return true;
}
}
}
return false;
}
private static boolean containOf(int[] arr, int child) {
for (int i : arr) {
if (i == child)
return true;
}
return false;
}
private static void reset() {
mInput[0] = 1;
mInput[1] = 2;
mInput[2] = 3;
mInput[3] = 0;
mInput[4] = 4;
mInput[5] = 5;
mInput[6] = 6;
stepPosition = 0;
}
}
Arnao1回答
-
慕标5263832
太长不阅
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相关分类
Java