add 883

fishercoder1534 · fishercoder1534 · commit 8d43b4b3c4f2 · 2020-02-12T20:49:38.000-08:00
diff --git a/src/main/java/com/fishercoder/solutions/_883.java b/src/main/java/com/fishercoder/solutions/_883.java
@@ -0,0 +1,60 @@
+package com.fishercoder.solutions;
+
+/**
+ * 883. Projection Area of 3D Shapes
+ *
+ * On a N * N grid, we place some 1 * 1 * 1 cubes that are axis-aligned with the x, y, and z axes.
+ * Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j).
+ * Now we view the projection of these cubes onto the xy, yz, and zx planes.
+ * A projection is like a shadow, that maps our 3 dimensional figure to a 2 dimensional plane.
+ * Here, we are viewing the "shadow" when looking at the cubes from the top, the front, and the side.
+ * Return the total area of all three projections.
+ *
+ * Example 1:
+ * Input: [[2]]
+ * Output: 5
+ *
+ * Example 2:
+ * Input: [[1,2],[3,4]]
+ * Output: 17
+ * Explanation:
+ * Here are the three projections ("shadows") of the shape made with each axis-aligned plane.
+ *
+ * Example 3:
+ * Input: [[1,0],[0,2]]
+ * Output: 8
+ *
+ * Example 4:
+ * Input: [[1,1,1],[1,0,1],[1,1,1]]
+ * Output: 14
+ *
+ * Example 5:
+ * Input: [[2,2,2],[2,1,2],[2,2,2]]
+ * Output: 21
+ *
+ * Note:
+ * 1 <= grid.length = grid[0].length <= 50
+ * 0 <= grid[i][j] <= 50
+ * */
+public class _883 {
+    public static class Solution1 {
+        /**credit: https://leetcode.com/problems/projection-area-of-3d-shapes/discuss/156726/C%2B%2BJavaPython-Straight-Forward-One-Pass*/
+        public int projectionArea(int[][] grid) {
+            int n = grid.length;
+            int area = 0;
+            for (int i = 0; i < n; i++) {
+                int x = 0;
+                int y = 0;
+                for (int j = 0; j < n; j++) {
+                    x = Math.max(x, grid[i][j]);
+                    y = Math.max(x, grid[j][i]);
+                    if (grid[i][j] > 0) {
+                        area++;
+                    }
+                }
+                area += x + y;
+            }
+            return area;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_883Test.java b/src/test/java/com/fishercoder/_883Test.java
@@ -0,0 +1,35 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._883;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _883Test {
+    private static _883.Solution1 solution1;
+    private static int[][] grid;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _883.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        grid = new int[][]{
+                {2}
+        };
+        assertEquals(5, solution1.projectionArea(grid));
+    }
+
+    @Test
+    public void test2() {
+        grid = new int[][]{
+                {1, 2},
+                {3, 4},
+        };
+        assertEquals(17, solution1.projectionArea(grid));
+    }
+
+}
