solution IQ1001 and PO3 by java

Author: xiao2shiqi

src/main/java/InterviewQuestions1001.java

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+import java.util.Arrays;
+
+/**
+ * LC#IQ10.01：合并排序数组
+ * Link: https://leetcode-cn.com/problems/sorted-merge-lcci/
+ * 思路1：合并后排序 （效率低）
+ * 思路2：使用 k 从尾部开始往头插入元素（最优）
+ */
+public class InterviewQuestions1001 {
+
+    public static void merge(int[] A, int m, int[] B, int n) {
+        int k = m + n - 1;
+        int i = m - 1;
+        int j = n - 1;
+        while (i >= 0 && j >= 0) {
+            if (A[i] < B[j]) {
+                A[k--] = B[j--];
+            } else {
+                A[k--] = A[i--];
+            }
+        }
+        while (j >= 0) {  A[k--] = B[j--]; }
+    }
+
+    public static void main(String[] args) {
+//        int[] nums1 = {1,2,3,0,0,0};
+//        int[] nums2 = {2,5,6};
+        int[] nums1 = {0};
+        int[] nums2 = {1};
+        merge(nums1, 0, nums2, 1);
+        System.out.println(Arrays.toString(nums1));
+    }
+}

src/main/java/PointerOffer3.java

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+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * LC#OF03: 数组中重复的数字
+ * Link：https://leetcode-cn.com/problems/shu-zu-zhong-zhong-fu-de-shu-zi-lcof/
+ * 思路：哈希排重
+ */
+public class PointerOffer3 {
+
+    public static int findRepeatNumber(int[] nums) {
+        Set<Integer> hashSet = new HashSet<>(nums.length);
+        for (int num : nums) {
+            if (hashSet.contains(num)) return num;
+            hashSet.add(num);
+        }
+        return -1;
+    }
+
+    public static void main(String[] args) {
+        int[] nums = {2, 3, 1, 0, 2, 5, 3};
+        int res = findRepeatNumber(nums);
+        System.out.println(res);
+    }
+}