add 1232

Author: fishercoder1534

README.md

@@ -13,6 +13,7 @@ _If you like this project, please leave me a star._ ★
 |1252|[Cells with Odd Values in a Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1252.java) | O(m*n + k) | O(m*n) | |Easy||
 |1237|[Find Positive Integer Solution for a Given Equation](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1237.java) | | | |Easy||
 |1243|[Array Transformation](https://leetcode.com/problems/array-transformation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1243.java) |  |  | [:tv:](https://www.youtube.com/watch?v=MQ2i4T1l-Gs)|Easy||
+|1232|[Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1232.java) |  |  | |Easy||
 |1217|[Play with Chips](https://leetcode.com/problems/play-with-chips/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1217.java) |  |  | |Easy||
 |1213|[Intersection of Three Sorted Arrays](https://leetcode.com/problems/intersection-of-three-sorted-arrays/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1213.java) |  |  | [:tv:](https://www.youtube.com/watch?v=zceoOrHSHNQ)|Easy||
 |1207|[Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1207.java) | O(n) | O(1) | [:tv:](https://www.youtube.com/watch?v=_NYimlZY1PE)|Easy||

src/main/java/com/fishercoder/solutions/_1232.java

@@ -0,0 +1,44 @@
+package com.fishercoder.solutions;
+
+/**
+ * 1232. Check If It Is a Straight Line
+ *
+ * You are given an array coordinates, coordinates[i] = [x, y],
+ * where [x, y] represents the coordinate of a point.
+ * Check if these points make a straight line in the XY plane.
+ *
+ * Example 1:
+ * Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
+ * Output: true
+ *
+ * Example 2:
+ * Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
+ * Output: false
+ *
+ * Constraints:
+ * 2 <= coordinates.length <= 1000
+ * coordinates[i].length == 2
+ * -10^4 <= coordinates[i][0], coordinates[i][1] <= 10^4
+ * coordinates contains no duplicate point.
+ * */
+public class _1232 {
+    public static class Solution1 {
+        /**
+         * To check if they share the same slope, we use this formula:
+         *
+         * check whether (y4 - y3)/(x4- x3) equals to (y2 - y1)/(x2 - x1)
+         * considering denominator could be zero, we'll change it to use multiplication instead of division,
+         * thus it becomes
+         * check whether (y4 - y3)*(x2 - x1) equals (x4 - x3)*(y2 - y1)
+         * */
+        public boolean checkStraightLine(int[][] coordinates) {
+            for (int i = 2; i < coordinates.length - 1; i++) {
+                if ((coordinates[1][0] - coordinates[0][0]) * (coordinates[i + 1][1] - coordinates[i][1]) !=
+                        (coordinates[1][1] - coordinates[0][1]) * (coordinates[i + 1][0] - coordinates[i][0])) {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+}

src/test/java/com/fishercoder/_1232Test.java

@@ -0,0 +1,67 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1232;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _1232Test {
+    private static _1232.Solution1 solution1;
+    private static int[][] coordinates;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1232.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        coordinates = new int[][]{
+                {1, 2},
+                {2, 3},
+                {3, 4},
+                {4, 5},
+                {5, 6},
+                {6, 7}
+        };
+        assertEquals(true, solution1.checkStraightLine(coordinates));
+    }
+
+    @Test
+    public void test2() {
+        coordinates = new int[][]{
+                {1, 1},
+                {2, 2},
+                {3, 4},
+                {4, 5},
+                {5, 6},
+                {7, 7}
+        };
+        assertEquals(false, solution1.checkStraightLine(coordinates));
+    }
+
+    @Test
+    public void test3() {
+        coordinates = new int[][]{
+                {-3, -2},
+                {-1, -2},
+                {2, -2},
+                {-2, -2},
+                {0, -2}
+        };
+        assertEquals(true, solution1.checkStraightLine(coordinates));
+    }
+
+    @Test
+    public void test4() {
+        coordinates = new int[][]{
+                {0, 1},
+                {1, 3},
+                {-4, -7},
+                {5, 11}
+        };
+        assertEquals(true, solution1.checkStraightLine(coordinates));
+    }
+
+}