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83 lines
1.9 KiB
Markdown
83 lines
1.9 KiB
Markdown
# [1380. Lucky Numbers in a Matrix](https://leetcode.com/problems/lucky-numbers-in-a-matrix/)
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## 题目
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Given a `m * n` matrix of **distinct** numbers, return all lucky numbers in the matrix in **any** order.
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A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.
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**Example 1**:
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```
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Input: matrix = [[3,7,8],[9,11,13],[15,16,17]]
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Output: [15]
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Explanation: 15 is the only lucky number since it is the minimum in its row and the maximum in its column
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```
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**Example 2**:
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```
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Input: matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
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Output: [12]
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Explanation: 12 is the only lucky number since it is the minimum in its row and the maximum in its column.
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```
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**Example 3**:
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```
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Input: matrix = [[7,8],[1,2]]
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Output: [7]
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```
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**Constraints**:
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- `m == mat.length`
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- `n == mat[i].length`
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- `1 <= n, m <= 50`
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- `1 <= matrix[i][j] <= 10^5`.
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- All elements in the matrix are distinct.
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## 题目大意
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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：
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- 在同一行的所有元素中最小
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- 在同一列的所有元素中最大
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## 解题思路
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- 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。
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- 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。
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## 代码
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```go
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func luckyNumbers(matrix [][]int) []int {
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t, r, res := make([]int, len(matrix[0])), make([]int, len(matrix[0])), []int{}
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for _, val := range matrix {
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m, k := val[0], 0
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for j := 0; j < len(matrix[0]); j++ {
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if val[j] < m {
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m = val[j]
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k = j
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}
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if t[j] < val[j] {
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t[j] = val[j]
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}
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}
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if t[k] == m {
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r[k] = m
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}
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}
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for k, v := range r {
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if v > 0 && v == t[k] {
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res = append(res, v)
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}
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}
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return res
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}
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``` |