[염혜정] Day17

leetcode3/염혜정/463. Island Perimeter.java

@@ -0,0 +1,47 @@
+// 인접한 1의 개수를 구한다.
+// 1 -> 3, 2 -> 2, 3 -> 1, 4 -> 0
+
+class Solution {
+    static int[] dx = {-1, 1, 0, 0};
+    static int[] dy = {0, 0, -1, 1};
+
+    public int islandPerimeter(int[][] grid) {
+        int sum = 0;
+        for (int i = 0; i<grid.length; i++) {
+            for (int k = 0; k<grid[0].length; k++) {
+                if (grid[i][k] == 0) continue;
+                int cnt = adjacentCnt(grid, i, k);
+                sum += calAdjacent(cnt);
+            }
+        }
+        return sum;
+    }
+
+    int adjacentCnt (int[][] grid, int x, int y) {
+        int cnt = 0;
+
+        for (int i = 0; i<4; i++) {
+            int nx = x + dx[i];
+            int ny = y + dy[i];
+
+            if (nx < 0 || ny < 0 || nx >= grid.length || ny >= grid[0].length) continue;
+            if (grid[nx][ny] == 1) cnt++;
+        }
+        return cnt;
+    }
+
+    int calAdjacent(int num) {
+        switch (num) {
+            case 0:
+                return 4;
+            case 1:
+                return 3;
+            case 2:
+                return 2;
+            case 3:
+                return 1;
+            default:
+                return 0;
+            }
+    }
+}