Build Tower

题目

Build Tower
Build Tower by the following given argument:
number of floors (integer and always greater than 0).

Tower block is represented as *

Python: return a list;
JavaScript: returns an Array;
C#: returns a string[];
PHP: returns an array;
C++: returns a vector;
Haskell: returns a [String];
Ruby: returns an Array;
Lua: returns a Table;
Have fun!

for example, a tower of 3 floors looks like below

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[
  '  *  ', 
  ' *** ', 
  '*****'
]

and a tower of 6 floors looks like below

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[
  '     *     ', 
  '    ***    ', 
  '   *****   ', 
  '  *******  ', 
  ' ********* ', 
  '***********'
]

思路

确定每行的星号和空格的数量，然后组合到一起，最后组合数组。

答案

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function towerBuilder(nFloors) {
    // 新建数组
    var arr = new Array();
    // 确定最后一行的星号数量
    var n_bottom = nFloors * 2 - 1;
    // 绘制每一行
    for (var i = 1; i <= nFloors; i++) {
        var n_space = nFloors - i;
        var n_asterisk = i * 2 - 1;
        var f_space = new String();
        var f_asterisk = new String();
        for (var j = 0; j < n_space; j++) {
            f_space += " ";
        }
        for (var j = 0; j < n_asterisk; j++) {
            f_asterisk += "*";
        }
        var floor = f_space + f_asterisk + f_space;
        arr.push(floor);
    }
    return arr;
}