73: Set Matrix Zeroes

Author: emanuelschmoczer

README.md

@@ -12,6 +12,7 @@ My solutions to LeetCode problems in Kotlin.
 |                      [20](https://leetcode.com/problems/valid-parentheses/)                      |                    [Valid Parentheses](src/main/kotlin/com/schmoczer/leetcode/_0020/ValidParentheses.kt)                     |    Easy    |
 |                     [42](https://leetcode.com/problems/trapping-rain-water/)                     |                   [Trapping Rain Water](src/main/kotlin/com/schmoczer/leetcode/_0042/TrappingRainWater.kt)                   |    Hard    |
 |                       [49](https://leetcode.com/problems/group-anagrams/)                        |                       [Group Anagrams](src/main/kotlin/com/schmoczer/leetcode/_0049/GroupAnagrams.kt)                        |   Medium   |
+|                      [73](https://leetcode.com/problems/set-matrix-zeroes/)                      |                     [Set Matrix Zeroes](src/main/kotlin/com/schmoczer/leetcode/_0073/SetMatrixZeroes.kt)                     |   Medium   |
 |                      [125](https://leetcode.com/problems/valid-palindrome/)                      |                     [Valid Palindrome](src/main/kotlin/com/schmoczer/leetcode/_0125/ValidPalindrome.kt)                      |    Easy    |
 |                 [151](https://leetcode.com/problems/reverse-words-in-a-string/)                  |              [Reverse Words in a String](src/main/kotlin/com/schmoczer/leetcode/_0151/ReverseWordsInString.kt)               |   Medium   |
 |                [186](https://leetcode.com/problems/reverse-words-in-a-string-ii/)                |         [Reverse Words in a String II](src/main/kotlin/com/schmoczer/leetcode/_0186/ReverseWordsInStringInPlace.kt)          |   Medium   |

src/main/kotlin/com/schmoczer/leetcode/_0073/README.md

@@ -0,0 +1,25 @@
+# Set Matrix Zeroes
+
+Given an `m x n` integer matrix `matrix`, if an element is `0`, set its entire row and column to `0`'s.
+
+You must do it in place.
+
+Example 1:
+
+> Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]
+>
+> Output: [[1,0,1],[0,0,0],[1,0,1]]
+
+Example 2:
+
+> Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]
+>
+> Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]
+
+
+Constraints:
+
+- `m == matrix.length`
+- `n == matrix[0].length`
+- `1 <= m, n <= 200`
+- `-2^31 <= matrix[i][j] <= 2^31 - 1`

src/main/kotlin/com/schmoczer/leetcode/_0073/SetMatrixZeroes.kt

@@ -0,0 +1,22 @@
+package com.schmoczer.leetcode._0073
+
+class SetMatrixZeroes {
+    fun setZeroes(matrix: Array<IntArray>) {
+        val foundZeroes = mutableListOf<Pair<Int, Int>>()
+        for (i in 0 until matrix.size) {
+            for (j in 0 until matrix.first().size) {
+                if (matrix[i][j] == 0) {
+                    foundZeroes.add(Pair(i, j))
+                }
+            }
+        }
+        for (foundZero in foundZeroes) {
+            for (i in 0 until matrix.first().size) {
+                matrix[foundZero.first][i] = 0
+            }
+            for (i in 0 until matrix.size) {
+                matrix[i][foundZero.second] = 0
+            }
+        }
+    }
+}

src/test/kotlin/com/schmoczer/leetcode/_0073/SetMatrixZeroesTest.kt

@@ -0,0 +1,38 @@
+package com.schmoczer.leetcode._0073
+
+import org.junit.jupiter.api.BeforeEach
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+
+class SetMatrixZeroesTest {
+    private lateinit var sut: SetMatrixZeroes
+
+    @BeforeEach
+    fun setUp() {
+        sut = SetMatrixZeroes()
+    }
+
+    @Test
+    fun `set zeroes on 3x3 matrix`() {
+        val input = arrayOf(intArrayOf(1, 1, 1), intArrayOf(1, 0, 1), intArrayOf(1, 1, 1))
+        val expected = arrayOf(intArrayOf(1, 0, 1), intArrayOf(0, 0, 0), intArrayOf(1, 0, 1))
+
+        sut.setZeroes(input)
+
+        for (i in 0 until expected.size) {
+            assertContentEquals(expected[i], input[i])
+        }
+    }
+
+    @Test
+    fun `set zeroes on 3x4 matrix`() {
+        val input = arrayOf(intArrayOf(0, 1, 2, 0), intArrayOf(3, 4, 5, 2), intArrayOf(1, 3, 1, 5))
+        val expected = arrayOf(intArrayOf(0, 0, 0, 0), intArrayOf(0, 4, 5, 0), intArrayOf(0, 3, 1, 0))
+
+        sut.setZeroes(input)
+
+        for (i in 0 until expected.size) {
+            assertContentEquals(expected[i], input[i])
+        }
+    }
+}