From a6d2698c40cabd0bc3cad9a6165e7e3c1989617f Mon Sep 17 00:00:00 2001 From: Havan Date: Sun, 21 Apr 2019 15:11:43 -0700 Subject: [PATCH] Add solution for 1020 --- README.md | 1 + .../java/com/fishercoder/solutions/_1020.java | 53 ++++++++++++++++++ src/test/java/com/fishercoder/_1020Test.java | 54 +++++++++++++++++++ 3 files changed, 108 insertions(+) create mode 100644 src/main/java/com/fishercoder/solutions/_1020.java create mode 100644 src/test/java/com/fishercoder/_1020Test.java diff --git a/README.md b/README.md index 079377933c..9f27fc5088 100644 --- a/README.md +++ b/README.md @@ -29,6 +29,7 @@ Your ideas/fixes/algorithms are more than welcome! |-----|----------------|---------------|---------------|---------------|--------|-------------|------------- |1022|[Sum of Root To Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1022.java) | O(n) | O(n) | |Easy| |1021|[Remove Outermost Parentheses](https://leetcode.com/problems/remove-outermost-parentheses/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1021.java) | O(n) | O(n) | |Easy| +|1020|[Number of Enclaves](https://leetcode.com/problems/number-of-enclaves/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1020.java) | O(mn) | O(mn) | |Medium|Graph, DFS, BFS, recursion| |1018|[Binary Prefix Divisible By 5](https://leetcode.com/problems/binary-prefix-divisible-by-5/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1018.java) | O(n) | O(1) | |Easy| |1013|[Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1013.java) | O(n) | O(1) | |Easy| |1009|[Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1009.java) | O(n) | O(1) | |Easy| diff --git a/src/main/java/com/fishercoder/solutions/_1020.java b/src/main/java/com/fishercoder/solutions/_1020.java new file mode 100644 index 0000000000..eec5f59fc8 --- /dev/null +++ b/src/main/java/com/fishercoder/solutions/_1020.java @@ -0,0 +1,53 @@ +package com.fishercoder.solutions; + +/** + * Given a 2D array A, each cell is 0 (representing sea) or 1 (representing land) + * + * A move consists of walking from one land square 4-directionally to another land square, or off the boundary of the grid. + * + * Return the number of land squares in the grid for which we cannot walk off the boundary of the grid in any number of moves. + */ + +public class _1020 { + public static class Solution1 { + public void walk(int[][] A, boolean[][] visited, int x, int y) { + if (x >= A.length || x < 0 || y >= A[0].length || y < 0) return; + if (visited[x][y]) return; + if (A[x][y] == 0) return; + + visited[x][y] = true; + + walk(A, visited, x - 1, y); + walk(A, visited, x, y - 1); + walk(A, visited, x, y + 1); + walk(A, visited, x + 1, y); + } + + public int numEnclaves(int[][] A) { + int n = A.length; + int m = A[0].length; + boolean[][] visited = new boolean[n][m]; + + for (int i = 0; i < n; ++i) { + walk(A, visited, i, 0); + walk(A, visited, i, m - 1); + } + + for (int j = 0; j < m; ++j) { + walk(A, visited, 0, j); + walk(A, visited, n - 1, j); + } + + int unreachables = 0; + for (int i = 0; i < n; ++i) { + for (int j = 0; j < m; ++j) { + if (A[i][j] == 1 && !visited[i][j]) { + ++unreachables; + } + } + } + + return unreachables; + } + } +} diff --git a/src/test/java/com/fishercoder/_1020Test.java b/src/test/java/com/fishercoder/_1020Test.java new file mode 100644 index 0000000000..359557c6c3 --- /dev/null +++ b/src/test/java/com/fishercoder/_1020Test.java @@ -0,0 +1,54 @@ +package com.fishercoder; + +import com.fishercoder.solutions._1020; +import org.junit.BeforeClass; +import org.junit.Test; + +import static org.junit.Assert.assertEquals; + +public class _1020Test { + private static _1020.Solution1 solution1; + + @BeforeClass + public static void setup() { + solution1 = new _1020.Solution1(); + } + + @Test + public void test1() { + int[][] map = { + {0, 0, 0, 0}, + {1, 0, 1, 0}, + {0, 1, 1, 0}, + {0, 0, 0, 0} + }; + + assertEquals(solution1.numEnclaves(map), 3); + } + + @Test + public void test2() { + int[][] map = { + {0, 1, 1, 0}, + {0, 0, 1, 0}, + {0, 0, 1, 0}, + {0, 0, 0, 0} + }; + + assertEquals(solution1.numEnclaves(map), 0); + } + + @Test + public void test3() { + int[][] map = { + {0, 1, 1, 0}, + {0, 0, 0, 0}, + {1, 0, 1, 0}, + {1, 0, 0, 0}, + {0, 1, 1, 0}, + {0, 0, 0, 0}, + }; + + assertEquals(solution1.numEnclaves(map), 3); + } +} pFad - Phonifier reborn

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