我在使用加权快速联合的java中的渗透程序遇到问题我认为主要的错误是我使用union来判断哪些位置已连接或者我正在运行的测试存在问题如果网格渗透，如果有人有一些反馈我会很感激。
/* a class to test for percolation of an N by N grid*/
public class Percolation{
WeightedQuickUnionUF uf;
boolean[][] grid;
public int size;
int opensites;//keeps track of open sites
/*Constructor for Percolation that takes N as an argument
* to create an N*N grid
**/
public Percolation(int N){
this.size=N;
int spaces= N*N;
uf = new WeightedQuickUnionUF(spaces+1);//initializes the WQUUF data structure.
opensites=0;//intializes open sites to 0.
this.grid = new boolean[N][N];// makes a boolean array 2D N by N representing the grid
for(int i=0;i<N;i++){//i represents the x coordinate
for(int j=0;j<N;j++){// j represents the y coordinate
grid[i][j]=false; //sets all spaces as closed
}//end j loop
}//end i loop
for(int i=0;i<size;i++){
uf.union(size*size,i);
}// end for that connects all top sites
}// end constructor;
/*
* takes to ints as X and Y coordinates
* and opens that square on the grid
**/
public void open(int i, int j){
if(!(this.grid[i][j])){
this.grid[i][j]=true;
opensites+=1;
}
}//end open
/*
* takes to ints as X and Y coordinates and
* returns true if that space is open and false
* if not
**/
public boolean isOpen(int i, int j){
return grid[i][j];
}//end isOpen
/*
* takes to ints as X and Y coordinates and
* returns true if that space is full and false
* if not
*/
public boolean isFull(int i, int j){
if(isOpen(i,j)){
if(uf.connected((i+j*size),(size*size))){ return true;}
}//end for
return false;
}//end isFull
/*
* checks if any space on the bottom is full returns true
* if there is one false other wise
*/
public boolean percolates(){
for(int i=0;i<size;i++){
if(isFull(i,size-1)) return true;
}
return false;
}//end percolates
/*
* prints out grid
* ---------------------
* 0 false true false
* 1 true true true
* 2 false true true
* ---------------------
*/
public void printGrid(){
StdOut.println("----------------------------------");
for(int x = 0;x < size;x++){
for(int y = 0; y < size; y++){
String mark=isOpen(x,y) ? "x": "0";
StdOut.print("|"+mark+"|");
}
StdOut.println();
}
StdOut.println("----------------------------------");
}
/*
* Main method takes two int arguments one for the number
* of tests to be run and one for the size of the grid
**/
public static void main(String[] args) {
int tests=StdIn.readInt();
int size=StdIn.readInt();
int testedTimes=1;
int spaces=size*size-1;
int check=0;
int space=0;
while(testedTimes<=tests){
Percolation perc = new Percolation(size);
StdOut.println("Before anything");
perc.printGrid();
while(!perc.percolates()){
int x=StdRandom.uniform(0,size);
int y=StdRandom.uniform(0,size);
perc.open(x,y);
space=x+(y*size);
if((space+1<spaces)&&(x<size-1)){//right 1
if(perc.isOpen(x+1,y)){
perc.uf.union(space,space+1);
}
}
if((space-1>0)&&(x>0)){//left 1
if(perc.isOpen(x-1,y)){
perc.uf.union(space,space-1);
}
}
if((space-size>0)&&(y-1>0)){//up 1
if(perc.isOpen(x,y-1)){
perc.uf.union(space,space-size);
}
}
if((space+size<spaces)&&(y+1<=size)){//down 1
if((perc.isOpen(x,y+1))){
perc.uf.union(space,space+size);
}
perc.printGrid();
}
}//end while(!percolates())
testedTimes++;
}//end while(TestedTimes<tests)
}//end main.
}//end class
答案 0 :(得分：3)
在我看来，你是从左到右渗透而不是从顶部到按钮（你使用i作为列，j作为行）。
尝试更改printGrid，使用isOpen（y，x）代替isOpen（x，y）。
答案 1 :(得分：0)
import edu.princeton.cs.algs4.WeightedQuickUnionUF;
public class Percolation {
private boolean[][] grid;
private int len;
private int top = 0;
private int bottom;
private WeightedQuickUnionUF uf;
private int count = 0;
// creates n-by-n grid, with all sites initially blocked
public Percolation(int n) {
if (n <= 0) {
throw new IllegalArgumentException();
}
len = n;
grid = new boolean[n][n];
bottom = n * n + 1;
uf = new WeightedQuickUnionUF(n * n + 2);
}
// opens the site (row, col) if it is not open already
public void open(int row, int col) {
if (row < 1 || col < 1 || row > len || col > len) {
throw new IllegalArgumentException();
}
int i = row - 1;
int j = col - 1;
if (!isOpen(row, col)) {
count++;
grid[i][j] = true;
if (row == 1) {
uf.union(getIndex(row, col), top);
}
if (row == len) {
uf.union(getIndex(row, col), bottom);
}
// union the neighbors
// down
if (row < len && isOpen(row + 1, col)) {
uf.union(getIndex(row, col), getIndex(row + 1, col));
}
// up
if (row > 1 && isOpen(row - 1, col)) {
uf.union(getIndex(row, col), getIndex(row - 1, col));
}
// left
if (col > 1 && isOpen(row, col - 1)) {
uf.union(getIndex(row, col), getIndex(row, col - 1));
}
// right
if (col < len && isOpen(row, col + 1)) {
uf.union(getIndex(row, col), getIndex(row, col + 1));
}
}
}
// is the site (row, col) open?
public boolean isOpen(int row, int col) {
if (row < 1 || col < 1 || row > len || col > len) {
throw new IllegalArgumentException();
}
return grid[row - 1][col - 1];
}
// is the site (row, col) full?
public boolean isFull(int row, int col) {
if (row < 1 || col < 1 || row > len || col > len) {
throw new IllegalArgumentException();
}
return (uf.find(getIndex(row, col)) == uf.find(top));
}
// returns the number of open sites
public int numberOfOpenSites() {
return count;
}
// does the system percolate?
public boolean percolates() {
return (uf.find(top) == uf.find(bottom));
}
// get the index if row,column
private int getIndex(int row, int col) {
return len * (row - 1) + (col);
}
// test client (optional)
public static void main(String[] args) {
}
}