Swift 快速创建二维数组

extension Array {
    static func array2d<T>(row: Int, column: Int, value: T) -> [[T]] {
        let arr = Array<T>(repeating: value, count: column)
        return Array<[T]>(repeating: arr, count: row)
    }
}

let visited = Array<Bool>.array2d(row: 3, column: 1, value: false) // Bool visited[3][1];
var dp = Array<Int>.array2d(row: 4, column: 2, value: 0) // int dp[4][2];