1380. Lucky Numbers in a Matrix

# 1380. Lucky Numbers in a Matrix#

## 题目 #

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: 
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: 
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: 
``````

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.

• 在同一行的所有元素中最小
• 在同一列的所有元素中最大

## 解题思路 #

• 找出矩阵中的幸运数。幸运数的定义：同时满足 2 个条件，在同一行的所有元素中最小并且在同一列的所有元素中最大。
• 简单题。按照题意遍历矩阵，找到同时满足 2 个条件的数输出即可。

## 代码 #

``````
package leetcode

func luckyNumbers(matrix [][]int) []int {
t, r, res := make([]int, len(matrix)), make([]int, len(matrix)), []int{}
for _, val := range matrix {
m, k := val, 0
for j := 0; j < len(matrix); j++ {
if val[j] < m {
m = val[j]
k = j
}
if t[j] < val[j] {
t[j] = val[j]
}
}

if t[k] == m {
r[k] = m
}
}
for k, v := range r {
if v > 0 && v == t[k] {
res = append(res, v)
}
}
return res
}

`````` Sep 11, 2022 Edit this page