Number of Distinct Islands

Description

null

Solution(javascript)

/**
 * @param {number[][]} grid
 * @return {number}
 */
const numDistinctIslands = function (grid) {
  const visited = grid.map(x => x.map(() => false))
  const dfs = (row, column, p) => {
    if (row < 0 || row > grid.length - 1
      || column < 0 || column > grid[row].length - 1
    ) {
      return p
    }
    if (visited[row][column]) {
      return p
    }
    visited[row][column] = true
    if (grid[row][column] === 0) {
      return p
    }

    p = dfs(row + 1, column, `${p}d`)
    p = dfs(row - 1, column, `${p}u`)
    p = dfs(row, column - 1, `${p}l`)
    p = dfs(row, column + 1, `${p}r`)
    return p
  }
  const set = new Set()
  for (let i = 0; i < grid.length; i++) {
    for (let j = 0; j < grid[i].length; j++) {
      if (grid[i][j] === 1 && !visited[i][j]) {
        const path = dfs(i, j, 'o')
        set.add(path)
      }
    }
  }
  return set.size
}