滑动窗口最大值、有效括号生成、

src/main/java/com/github/songjiang951130/leetcode/backtrack/LetterCombination.java

@@ -39,4 +39,40 @@ private void dfs(String digits, int i, List<String> res, String tempResult) {
             dfs(digits, i + 1, res, tempResult + c);
         }
     }
+
+    public List<String> generateParenthesis(int n) {
+        char[] chars = new char[n * 2];
+        List<String> res = new ArrayList<>();
+        generate(chars, 0, 2 * n, res);
+        return res;
+    }
+
+    private void generate(char[] chars, int i, int len, List<String> res) {
+        if (i == len) {
+            if (validValue(chars)) {
+                res.add(new String(chars));
+            }
+            return;
+        }
+
+        chars[i] = '(';
+        generate(chars, i + 1, len, res);
+        chars[i] = ')';
+        generate(chars, i + 1, len, res);
+    }
+
+    private boolean validValue(char[] chars) {
+        int left = 0;
+        for (int i = 0; i < chars.length; i++) {
+            if (chars[i] == '(') {
+                left++;
+            } else if (chars[i] == ')') {
+                left--;
+            }
+            if (left < 0) {
+                return false;
+            }
+        }
+        return left == 0;
+    }
 }

src/main/java/com/github/songjiang951130/leetcode/heap/ArrayMax.java

@@ -0,0 +1,61 @@
+package com.github.songjiang951130.leetcode.heap;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class ArrayMax {
+
+    /**
+     * 思路记录：滑动窗口 打算用linked list。做队列，然后用生成一个队列最大值 max；
+     * 出队的时候元素a 比较max 1、如果 a==max，重新生成队列最大值max；2、a < max 最大值存入res[] 3、a >max 不可能存在</>
+     *
+     * @param nums
+     * @param k
+     * @return
+     */
+    public int[] maxSlidingWindow(int[] nums, int k) {
+        int[] sw = new int[k];
+        int[] res = new int[nums.length - k + 1];
+        int max = Integer.MIN_VALUE;
+        for (int i = 0; i < k; i++) {
+            sw[i] = nums[i];
+            max = Math.max(max, sw[i]);
+        }
+        int index = 0;
+        res[index++] = max;
+
+        for (int i = k; i < nums.length; i++) {
+            int num = nums[i];
+            int offer = offer(sw);
+            add(sw, num);
+
+            if (offer == max) {
+                max = getMax(sw);
+            } else if (num > max) {
+                max = num;
+            }
+            res[index++] = max;
+        }
+        return res;
+    }
+
+    private int getMax(int[] array) {
+        int max = Integer.MIN_VALUE;
+        for (int i = 0; i < array.length; i++) {
+            max = Math.max(max, array[i]);
+        }
+        return max;
+    }
+
+    private int offer(int[] array) {
+        int res = array[0];
+        for (int i = 0; i < array.length - 1; i++) {
+            array[i] = array[i + 1];
+        }
+        return res;
+    }
+
+    private void add(int[] array, int val) {
+        array[array.length - 1] = val;
+    }
+}

src/test/java/com/github/songjiang951130/leetcode/backtrack/LetterCombinationTest.java

@@ -15,4 +15,9 @@ public void testLetterCombinations() {
         assertEquals(9, strings.size());
         assertEquals(Lists.newArrayList("ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"), strings);
     }
+
+    public void testGenerateParenthesis() {
+        List<String> strings = letterCombination.generateParenthesis(1);
+        System.out.println(strings);
+    }
 }

src/test/java/com/github/songjiang951130/leetcode/heap/ArrayMaxTest.java

@@ -0,0 +1,15 @@
+package com.github.songjiang951130.leetcode.heap;
+
+import junit.framework.TestCase;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class ArrayMaxTest extends TestCase {
+
+    public void testMaxSlidingWindow() {
+        //warning 超时
+        ArrayMax solution = new ArrayMax();
+        assertArrayEquals(new int[]{3, 3, 5, 5, 6, 7}, solution.maxSlidingWindow(new int[]{1, 3, -1, -3, 5, 3, 6, 7}, 3));
+        assertArrayEquals(new int[]{1}, solution.maxSlidingWindow(new int[]{1}, 1));
+    }
+}