add 1572

fishercoder1534 · fishercoder1534 · commit 6f861ca76720 · 2020-09-05T09:17:44.000-07:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1572|[Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1572.java) ||Array|Easy|
 |1567|[Maximum Length of Subarray With Positive Product](https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1567.java) |[:tv:](https://youtu.be/bFer5PdsgpY)|Greedy|Medium|
 |1566|[Detect Pattern of Length M Repeated K or More Times](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1566.java) |[:tv:](https://youtu.be/aJAV_VgmjdE)|Array|Easy|
 |1561|[Maximum Number of Coins You Can Get](https://leetcode.com/problems/maximum-number-of-coins-you-can-get/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1561.java) |[:tv:](https://youtu.be/hPe9Z3TiUrA)|Sort|Medium|
diff --git a/src/main/java/com/fishercoder/solutions/_1572.java b/src/main/java/com/fishercoder/solutions/_1572.java
@@ -0,0 +1,30 @@
+package com.fishercoder.solutions;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class _1572 {
+    public static class Solution1 {
+        public int diagonalSum(int[][] mat) {
+            int m = mat.length;
+            Set<Integer> added = new HashSet<>();
+            int sum = 0;
+            for (int i = 0; i < m; i++) {
+                for (int j = 0; j < m; j++) {
+                    if (i == j) {
+                        added.add(i * m + j);
+                        sum += mat[i][j];
+                    }
+                }
+            }
+            for (int i = 0; i < m; i++) {
+                for (int j = m - 1; j >= 0; j--) {
+                    if (i + j == m - 1 && added.add(i * m + j)) {
+                        sum += mat[i][j];
+                    }
+                }
+            }
+            return sum;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1572Test.java b/src/test/java/com/fishercoder/_1572Test.java
@@ -0,0 +1,47 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1572;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _1572Test {
+    private static _1572.Solution1 solution1;
+    private static int[][] mat;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1572.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        mat = new int[][]{
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 9}
+        };
+        assertEquals(25, solution1.diagonalSum(mat));
+    }
+
+    @Test
+    public void test2() {
+        mat = new int[][]{
+                {5}
+        };
+        assertEquals(5, solution1.diagonalSum(mat));
+    }
+
+    @Test
+    public void test3() {
+        mat = new int[][]{
+                {1, 1, 1, 1},
+                {1, 1, 1, 1},
+                {1, 1, 1, 1},
+                {1, 1, 1, 1},
+        };
+        assertEquals(8, solution1.diagonalSum(mat));
+    }
+
+}
