add number of islands

tg123 · tg123 · commit ea68d4f9bea0 · 2015-04-08T13:29:32.000+08:00
diff --git a/number-of-islands/README.md b/number-of-islands/README.md
diff --git a/number-of-islands/Solution.java b/number-of-islands/Solution.java
@@ -0,0 +1,53 @@
+public class Solution {
+
+    boolean allowed(int x, int y, final int mx, final int my, char[][] grid, boolean[][] visited){
+        return (x < mx) && (x >= 0)
+            && (y < my) && (y >= 0)
+            && (grid[x][y] == '1')
+            && (!visited[x][y]);
+    }
+
+    void travel(int x, int y, final int mx, final int my, char[][] grid, boolean[][] visited){
+
+        // x - 1, y
+        // x + 1, y
+        // x, y - 1
+        // x, y + 1
+
+        visited[x][y] = true;
+
+        for(int[] xy: new int[][]{{x - 1, y}, {x + 1, y}, {x, y - 1}, {x, y + 1}}){
+
+            int _x = xy[0];
+            int _y = xy[1];
+
+            if(allowed(_x, _y, mx, my, grid, visited)){
+                travel(_x, _y, mx, my, grid, visited);
+            }
+        }
+
+    }
+
+    public int numIslands(char[][] grid) {
+
+        final int mx = grid.length;
+        if(mx == 0) return 0;
+        final int my = grid[0].length;
+
+        int count = 0;
+        boolean[][] visited = new boolean[mx][my];
+
+        for(int x = 0; x < mx; x++){
+            for(int y = 0; y < my; y++){
+                if(allowed(x, y, mx, my, grid, visited)){
+
+                    travel(x, y, mx, my, grid, visited);
+
+                    count++;
+                }
+            }
+        }
+
+        return count;
+    }
+}
diff --git a/number-of-islands/index.md b/number-of-islands/index.md
@@ -0,0 +1,9 @@
+---
+layout: solution
+title: Number of Islands
+date: 2015-04-08 13:28:15+08:00
+leetcode_id: 200
+---
+{% assign leetcode_name = {{page.path | remove: '/index.md'}}  %}
+{% assign leetcode_readme = {{leetcode_name | append: '/README.md' | prepend: '_root/' }}  %}
+{% include {{leetcode_readme}} %}
