LeetCode 1380. 矩阵中的幸运数 Lucky Numbers in a Matrix
Table of Contents
一、中文版
给你一个 m * n 的矩阵,矩阵中的数字 各不相同 。请你按 任意 顺序返回矩阵中的所有幸运数。
幸运数是指矩阵中满足同时下列两个条件的元素:
在同一行的所有元素中最小
在同一列的所有元素中最大
示例 1:
输入:matrix = [[3,7,8],[9,11,13],[15,16,17]]
输出:[15]
解释:15 是唯一的幸运数,因为它是其所在行中的最小值,也是所在列中的最大值。
示例 2:
输入:matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
输出:[12]
解释:12 是唯一的幸运数,因为它是其所在行中的最小值,也是所在列中的最大值。
示例 3:
输入:matrix = [[7,8],[1,2]]
输出:[7]
提示:
m == mat.length
n == mat[i].length
1 <= n, m <= 50
1 <= matrix[i][j] <= 10^5
矩阵中的所有元素都是不同的
二、英文版
Given a m * n matrix of distinct numbers, return all lucky numbers in the matrix in any order. A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column. Example 1: Input: matrix = [[3,7,8],[9,11,13],[15,16,17]] Output: [15] Explanation: 15 is the only lucky number since it is the minimum in its row and the maximum in its column Example 2: Input: matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]] Output: [12] Explanation: 12 is the only lucky number since it is the minimum in its row and the maximum in its column. Example 3: Input: matrix = [[7,8],[1,2]] Output: [7] Constraints: m == mat.length n == mat[i].length 1 <= n, m <= 50 1 <= matrix[i][j] <= 10^5. All elements in the matrix are distinct. 来源:力扣(LeetCode) 链接:https://leetcode-cn.com/problems/lucky-numbers-in-a-matrix 著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。
三、My answer
class Solution: def luckyNumbers (self, matrix: List[List[int]]) -> List[int]: res = [] minnum_list = {} # 找到每一行的最小值,存入字典,key是数字,value是该数字的下标 for i in range(len(matrix)): # min_line = min(matrix[i]) min_num = matrix[i][0] column = 0 for j in range(len(matrix[i])): if matrix[i][j] < min_num: min_num = matrix[i][j] column = j minnum_list[min_num] = [i,column] print("minnum_list:",minnum_list) # 遍历字典 flag = 0 for key in minnum_list: max_col = minnum_list[key][1] # 找到对应列 print("max_col:",max_col) # 遍历该列,判断 key 是否为最大值 for row in range(len(matrix)): if matrix[row][max_col] > key: flag = 1 break if flag == 0: res.append(key) else: flag = 0 continue return res """ [[3,7,8],[9,11,13],[15,16,17]] [[1,10,4,2],[9,3,8,7],[15,16,17,12]] [[7,8],[1,2]] """
四、解题报告
先找到每一行中的最小元素,再逐个比较这些最小元素所在的列中,该元素是不是列中的最大值。如果是,放入结果集。