数组索引超出范围-2d至1d

debugcn 发表于 Dev

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我正在使用普林斯顿大学提出的algs4 8拼图程序。我在第二个for循环中得到了数组索引超出范围的异常。有人看到引发此异常的问题吗？我的板子类+相关方法如下：

public class Board {
 private final int[][] blocks;
 private final int N;

 // construct a board from an N-by-N array of blocks
 // (where blocks[i][j] = block in row i, column j)
    public Board(int[][] blocks){
     N = blocks.length;
     this.blocks = new int[N][];
     for (int i=0; i<N; i++){
      this.blocks[i] = Arrays.copyOf(blocks[i], N);
     }
    }

    // board dimension N
    public int dimension(){
     return this.N;
    }

   //is the board solvable? 
   public boolean isSolvable(){
      int inversions = 0; 
      List<Integer> convert = new ArrayList<>(); // convert 2d to 1d 
      for (int i = 0; i < blocks.length; i++){
          for (int j = 0; j < blocks[i].length; j++){
              convert.add(blocks[i][j]);
          }
      }
      for (int i = 0; i < blocks.length; i++){ //counts the number of inversions 
          if (convert.get(i) < convert.get(i-1)){ //ARRAYINDEXOUTOFBOUNDS -1
              inversions++; 
          }
      }
      if (inversions % 2 == 0){
          return true; //even 
      }
      return false; //odd 
  }

他们是

convert.get(i-1) 当i == 0时超出范围。

您可能应该更改循环的开始索引：

  for (int i = 1; i < blocks.length; i++){ //counts the number of inversions 
      if (convert.get(i) < convert.get(i-1)){ 
          inversions++; 
      }
  }

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