add

5.leetcode/src/com/fanxb/common/Q1.java

@@ -0,0 +1,45 @@
+package com.fanxb.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author fanxb
+ * @date 2021年12月26日 22:02
+ */
+public class Q1 {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer, Integer> numIndexMap = new HashMap<>(nums.length);
+        for (int i = 0; i < nums.length; i++) {
+            numIndexMap.put(nums[i], i);
+        }
+        int cur;
+        Integer targetIndex;
+        for (int i = 0; i < nums.length; i++) {
+            cur = nums[i];
+            targetIndex = numIndexMap.get(target - cur);
+            if (targetIndex != null && targetIndex > i) {
+                return new int[]{i, targetIndex};
+            }
+        }
+        return null;
+    }
+
+    /**
+     * 更优，一次循环即可
+     *
+     * @return int[]
+     * @author fanxb
+     * @date 2021/12/26 22:08
+     */
+    public int[] betterTwoSum(int[] nums, int target) {
+        Map<Integer, Integer> numIndexMap = new HashMap<>(nums.length);
+        for (int i = 0; i < nums.length; i++) {
+            if (numIndexMap.containsKey(target - nums[i])) {
+                return new int[]{numIndexMap.get(target - nums[i]), i};
+            }
+            numIndexMap.put(nums[i], i);
+        }
+        return null;
+    }
+}

5.leetcode/src/com/fanxb/common/Q1078.java

@@ -0,0 +1,20 @@
+package com.fanxb.common;
+
+import java.util.LinkedList;
+
+/**
+ * @author fanxb
+ * @date 2021年12月26日 21:54
+ */
+public class Q1078 {
+    public String[] findOcurrences(String text, String first, String second) {
+        LinkedList<String> res = new LinkedList<>();
+        String[] strs = text.split(" ");
+        for (int i = 0; i < strs.length - 2; i++) {
+            if (strs[i].equals(first) && strs[i + 1].equals(second)) {
+                res.add(strs[i + 2]);
+            }
+        }
+        return res.toArray(new String[0]);
+    }
+}

5.leetcode/src/com/fanxb/common/Q2.java

@@ -11,12 +11,68 @@ public class Q2 {
         int val;
         ListNode next;
 
+        public ListNode() {
+        }
+
         public ListNode(int val) {
             this.val = val;
         }
     }
 
-    public static void main(String[] args) {
+    public ListNode reverse(ListNode node) {
+        ListNode last = null, cur = node, next = node.next;
+        while (next != null) {
+            cur.next = last;
+            last = cur;
+            cur = next;
+            next = next.next;
+        }
+        cur.next = last;
+        return cur;
+    }
 
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+        l1 = reverse(l1);
+        l2 = reverse(l2);
+        ListNode res = new ListNode(0), last = null, cur = res, next;
+        while (l1 != null || l2 != null) {
+            int val = cur.val;
+            if (l1 != null) {
+                val += l1.val;
+                l1 = l1.next;
+            }
+            if (l2 != null) {
+                val += l2.val;
+                l2 = l2.next;
+            }
+            if (val >= 10) {
+                cur.val = val - 10;
+                next = new ListNode(1);
+            } else {
+                cur.val = val;
+                next = new ListNode(0);
+            }
+            last = cur;
+            cur.next = next;
+            cur = next;
+        }
+        if (last != null && cur.val == 0) {
+            last.next = null;
+        }
+        return res;
+    }
+
+    public static void main(String[] args) {
+        ListNode l1 = new ListNode(2);
+        l1.next = new ListNode(4);
+        l1.next.next = new ListNode(9);
+
+        ListNode l2 = new ListNode(5);
+        l2.next = new ListNode(6);
+        l2.next.next = new ListNode(4);
+        l2.next.next.next = new ListNode(9);
+
+        new Q2().addTwoNumbers(l1, l2);
+//        new Q2().addTwoNumbers(new ListNode(0), new ListNode(0));
     }
 }