面试题7 指定一个m*n的整数矩阵 如果(r, c)位置元素的元素是0 则将行 r 和列 c 整个变成0 -尊龙凯时

  public void mysolution(int[][] matrix){
    if(!isvalidmatrix(matrix))  return;
    int numofrows = matrix.length;
    int numofcols = matrix[0].length;
    boolean[] rows = new boolean[numofrows];
    boolean[] cols = new boolean[numofcols];
    for(int i=0; i){
      for(int j=0; j){
        if(matrix[i][j]==0){
          rows[i] = true;
          cols[j] = true;
        }
      }
    }
    for(int i=0; i)
      if(rows[i])
        for(int j=0; j;
    for(int i=0; i)
      if(cols[i])
        for(int j=0; j;
  }
  private boolean isvalidmatrix(int[][] a){
    if(a==null) return false;
    if(a.length==0) return false;
    if(a[0]==null)  return false;
    if(a[0].length==0)  return false;
    return true;
  }

  public void goodsolution(int[][] matrix){
    if(!isvalidmatrix(matrix))  return;
    int numofrows = matrix.length;
    int numofcols = matrix[0].length;
    boolean firstrowhaszero = false;
    boolean firstcolhaszero = false;
    for(int i=0; i){
      if(matrix[0][i]==0){
        firstrowhaszero = true;
        break;
      }
    }
    for(int i=0; i){
      if(matrix[i][0]==0){
        firstcolhaszero = true;
        break;
      }
    }
    for(int i=1; i){
      for(int j=1; j){
        if(matrix[i][j]==0){
          matrix[i][0] = 0;
          matrix[0][j] = 0;
        }
      }
    }
    for(int i=1; i)
      if(matrix[i][0]==0)
        nullifyrow(matrix, i);
    for(int i=1; i)
      if(matrix[0][i]==0)
        nullifycol(matrix, i);
    if(firstrowhaszero) nullifyrow(matrix, 0);
    if(firstcolhaszero) nullifycol(matrix, 0);
  }
  private void nullifyrow(int[][] a, int row){
    for(int i=0; i)
      a[row][i] = 0;
  }
  
  private void nullifycol(int[][] a, int col){
    for(int i=0; i)
      a[i][col] = 0;
  }