add: LocalMaximaInArray and MatrixSearch

Author: Jer3myYu

java/Binary Search/LocalMaximaInArray.java

@@ -0,0 +1,15 @@
+public class LocalMaximaInArray {
+    public int localMaximaInArray(int[] nums) {
+        int left = 0;
+        int right = nums.length - 1;
+        while (left < right) {
+            int mid = (left + right) / 2;
+            if (nums[mid] > nums[mid + 1]) {
+                right = mid;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return left;
+    }
+}

java/Binary Search/MatrixSearch.java

@@ -0,0 +1,22 @@
+public class MatrixSearch {
+    public boolean matrixSearch(int[][] matrix, int target) {
+        int m = matrix.length;
+        int n = matrix[0].length;
+        int left = 0;
+        int right = m * n - 1;
+        // Perform binary search to find the target.
+        while (left <= right) {
+            int mid = (left + right) / 2;
+            int r = mid / n;
+            int c = mid % n;
+            if (matrix[r][c] == target) {
+                return true;
+            } else if (matrix[r][c] > target) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return false;
+    }
+}