如何简化提取二维网格右下对角线字符串的Python代码且保持输出不变

右下方向对角线上的元素满足行索引+列索引的和相等，比如(0,1)和(1,0)的行+列都是1，属于同一条对角线，我们可以基于这个规律用基础语法实现，全程只用到循环、列表、字典这些入门知识点：

def diagsDownRight(M):
    row_count = len(M)
    col_count = len(M[0])
    # 字典存储所有对角线：key为行索引+列索引的和，value为对应对角线的字符列表
    diag_map = {}
    # 遍历网格中所有元素
    for row_idx in range(row_count):
        for col_idx in range(col_count):
            key = row_idx + col_idx
            # 首次遇到该key时初始化空列表
            if key not in diag_map:
                diag_map[key] = []
            # 把当前字符加入对应对角线的列表
            diag_map[key].append(M[row_idx][col_idx])
    # 按key从小到大排序，拼接为字符串后返回
    result = []
    for key in sorted(diag_map.keys()):
        result.append(''.join(diag_map[key]))
    return result

测试验证 #

用你提供的mystery网格测试：

mystery = [["r","a","w","b","i","t"],
           ["x","a","y","z","c","h"],
           ["p","q","b","e","i","e"],
           ["t","r","s","b","o","g"],
           ["u","w","x","v","i","t"],
           ["n","m","r","w","o","t"]]
print(diagsDownRight(mystery))

输出结果与原代码完全一致，功能完全相同。

内容的提问来源于stack exchange，提问作者Bruffff