diff --git a/src/main/java/cn/whaifree/leetCode/Array/LeetCode169.java b/src/main/java/cn/whaifree/leetCode/Array/LeetCode169.java index d1c0c8a..5fe0bf3 100644 --- a/src/main/java/cn/whaifree/leetCode/Array/LeetCode169.java +++ b/src/main/java/cn/whaifree/leetCode/Array/LeetCode169.java @@ -23,13 +23,19 @@ public class LeetCode169 /** * 遍历每个元素 * count 为现在出现最多的数 - * - 如果count = 0 + * - 如果count = 0 (表示发生了是和不是的变化) * - 这个元素出现的次数>=之前元素出现的个数 * 所以基准变为这个元素 * count = item == base : 1:-1 * * 如果是这个元素+1,不是这个元素-1 * + * cge5 cge5 cge7 + * 1 2 1 2 1 0 1 0 1 2 1 0 1 2 3 4 + * [7, 7, 5, 7, 5, 1 | 5, 7 | 5, 5, 7, 7 | 7, 7, 7, 7] + * 在遍历到数组中的第一个元素以及每个在 | 之后的元素时，candidate 都会因为 count 的值变为 0 而发生改变。最后一次 candidate 的值从 5 变为 7，也就是这个数组中的众数。 + * + * * @param nums * @return */ diff --git a/src/main/java/cn/whaifree/leetCode/Array/LeetCode189.java b/src/main/java/cn/whaifree/leetCode/Array/LeetCode189.java new file mode 100644 index 0000000..d1edec6 --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Array/LeetCode189.java @@ -0,0 +1,58 @@ +package cn.whaifree.leetCode.Array; + +import org.junit.Test; + +import java.util.Arrays; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 12:15 + * @注释 + */ +public class LeetCode189 { + @Test + public void test() + { + int[] nums = new int[]{-1}; + new Solution1().rotate(nums, 3); + System.out.println(Arrays.toString(nums)); + } + + + + class Solution { + public void rotate(int[] nums, int k) { + int[] newNums = new int[nums.length]; + for (int i = 0; i < newNums.length; i++) { + newNums[(i + k) % nums.length] = nums[i]; + } + System.arraycopy(newNums, 0, nums, 0, nums.length); + + } + + } + + class Solution1 { + public void rotate(int[] nums, int k) { + k %= nums.length; + reverse(nums, 0, nums.length - 1); + reverse(nums, 0, k - 1); + reverse(nums, k, nums.length - 1); + } + + public void reverse(int[] nums, int start, int end) { + while (start < end) { + swap(nums, start, end); + start++; + end--; + } + } + + public void swap(int[] nums, int i, int j) { + int temp = nums[i]; + nums[i] = nums[j]; + nums[j] = temp; + } + } +} diff --git a/src/main/java/cn/whaifree/leetCode/Array/LeetCode274.java b/src/main/java/cn/whaifree/leetCode/Array/LeetCode274.java new file mode 100644 index 0000000..9f1a4bb --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Array/LeetCode274.java @@ -0,0 +1,35 @@ +package cn.whaifree.leetCode.Array; + +import org.junit.Test; + +import java.util.Arrays; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 17:17 + * @注释 + */ +public class LeetCode274 { + @Test + public void test() + { + int[] nums = new int[]{1,3,1}; + System.out.println(new Solution().hIndex(nums)); + } + + class Solution { + public int hIndex(int[] citations) { + + Arrays.sort(citations); + + for (int i = 0; i < citations.length; i++) { + int h = citations.length - i; + if (citations[i] >= h) { + return h; + } + } + return 0; + } + } +} diff --git a/src/main/java/cn/whaifree/leetCode/Array/LeetCode80.java b/src/main/java/cn/whaifree/leetCode/Array/LeetCode80.java new file mode 100644 index 0000000..4b9fca8 --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Array/LeetCode80.java @@ -0,0 +1,61 @@ +package cn.whaifree.leetCode.Array; + +import org.junit.Test; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 16:23 + * @注释 + */ +public class LeetCode80 { + + @Test + public void test() { + int[] nums = new int[]{0, 0, 1, 1, 1, 1, 2, 3, 3}; + System.out.println(new Solution().removeDuplicates(nums)); + } + + class Solution { + /** + * 双指针 + * - 跳跃判断，如果不一样就让left向前，并赋值 + * + * @param nums + * @return + */ + public int removeDuplicates(int[] nums) { + if (nums.length < 3) return nums.length; + int leftSlow = 0; + int rightFast = 2; + while (rightFast < nums.length) { + if (nums[rightFast] != nums[leftSlow]) { + nums[leftSlow + 2] = nums[rightFast]; + leftSlow++; + } + rightFast++; + } + return leftSlow + 2; + } + } + + + class Solution1 { + /** + * + * + * @param nums + * @return + */ + public int removeDuplicates(int[] nums) { + // 数组中的一号和二号元素肯定不用删除 + int index = 2; + for(int i = 2 ; i < nums.length ; i++) { + if(nums[i] != nums[index-2]) { + nums[index++] = nums[i]; + } + } + return index; + } + } +} diff --git a/src/main/java/cn/whaifree/leetCode/Array/LeetCode88.java b/src/main/java/cn/whaifree/leetCode/Array/LeetCode88.java new file mode 100644 index 0000000..00f0205 --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Array/LeetCode88.java @@ -0,0 +1,48 @@ +package cn.whaifree.leetCode.Array; + +import org.junit.Test; + +import java.util.Arrays; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 16:11 + * @注释 + */ +public class LeetCode88 { + + @Test + public void test() + { + int[] nums1 = new int[]{1,2,3,0,0,0}; + int[] nums2 = new int[]{2,5,6}; + new Solution().merge(nums1, 3, nums2, 3); + System.out.println(Arrays.toString(nums1)); + } + + class Solution { + public void merge(int[] nums1, int m, int[] nums2, int n) { + int index = 0; + int[] res = new int[nums1.length]; + int index1 = 0; + int index2 = 0; + while (index1 < m && index2 < n) { + if (nums1[index1] < nums2[index2]) { + res[index++] = nums1[index1++]; + }else { + res[index++] = nums2[index2++]; + } + } + + while (index1 < m) { + res[index++] = nums1[index1++]; + } + while (index2 < n) { + res[index++] = nums2[index2++]; + } + + System.arraycopy(res, 0, nums1, 0, index); + } + } +} diff --git a/src/main/java/cn/whaifree/leetCode/Hash/LeetCode380.java b/src/main/java/cn/whaifree/leetCode/Hash/LeetCode380.java new file mode 100644 index 0000000..c6b3598 --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Hash/LeetCode380.java @@ -0,0 +1,76 @@ +package cn.whaifree.leetCode.Hash; + +import org.junit.Test; + +import java.util.*; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 19:18 + * @注释 + */ +public class LeetCode380 { + @Test + public void test() + { + // ["RandomizedSet","remove","remove","insert","getRandom","remove","insert"] + // [[],[0],[0],[0],[],[0],[0]] + RandomizedSet randomizedSet = new RandomizedSet(); + randomizedSet.remove(0); + randomizedSet.remove(0); + randomizedSet.insert(0); + randomizedSet.getRandom(); + randomizedSet.remove(0); + randomizedSet.insert(0); + } + + class RandomizedSet { + List list; + Map map; + Random random; + + public RandomizedSet() { + list = new ArrayList<>(); + map = new HashMap<>(); + random = new Random(); + } + + public boolean insert(int val) { + // 存在返回false + if (map.containsKey(val)) { + return false; + } + int size = list.size(); + list.add(size, val); + map.put(val, size); + return true; + } + + public boolean remove(int val) { + if (!map.containsKey(val)) { + return false; + } + Integer idx = map.get(val); // 删除的元素index + + + Integer lastElement = list.get(list.size() - 1); // 最后一个元素的值 + + + // 更新最后一个元素，覆盖原来的list + list.set(idx, lastElement); + map.put(lastElement, idx); + + // 删除元素放最后 + list.remove(list.size() - 1); + map.remove(val); + return true; + } + + + public int getRandom() { + return list.get(random.nextInt(list.size())); + } + } + +} diff --git a/src/main/java/cn/whaifree/leetCode/Tree/LeetCode124.java b/src/main/java/cn/whaifree/leetCode/Tree/LeetCode124.java new file mode 100644 index 0000000..4b9aeb5 --- /dev/null +++ b/src/main/java/cn/whaifree/leetCode/Tree/LeetCode124.java @@ -0,0 +1,56 @@ +package cn.whaifree.leetCode.Tree; + +import cn.whaifree.leetCode.model.TreeNode; +import org.junit.Test; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 15:05 + * @注释 + */ +public class LeetCode124 { + @Test + public void test() + { + + TreeNode treeNode = TreeNode.constructTreeByArray(1, 2, 3); + System.out.println(new Solution().maxPathSum(treeNode)); + } + + class Solution { + /** + * f + * a + * b c + *

+ * a有可能的路径 + * 1. f a c + * 2. f a b + * 3. b a c 不包含父亲节点 用b+a+c与max判断 + * + * @param root + * @return + */ + int max = Integer.MIN_VALUE; + public int maxPathSum(TreeNode root) { + maxPath(root); + return max; + } + public int maxPath(TreeNode root) { + if (root == null) { + return 0; + } + int left = maxPath(root.left); + int right = maxPath(root.right); + if (left < 0) { + left = 0; + } + if (right < 0) { + right = 0; + } + max = Math.max(max, left + right + root.val); // 如果是 b a c 既没有用父亲节点 + return Math.max(left, right) + root.val; + } + } +} diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode146.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode146.java new file mode 100644 index 0000000..b70d192 --- /dev/null +++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode146.java @@ -0,0 +1,80 @@ +package cn.whaifree.redo.redo_all_240721; + +import org.junit.Test; + +import java.util.LinkedHashMap; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 15:46 + * @注释 + */ +public class LeetCode146 { + + @Test + public void test() + { +// LRUCache cache = new LRUCache(2); +// cache.put(1, 1); +// cache.put(2, 2); +// System.out.println(cache.get(1)); +// cache.put(3, 3); +// System.out.println(cache.get(2)); +// cache.put(4, 4); +// System.out.println(cache.get(1)); +// System.out.println(cache.get(3)); +// System.out.println(cache.get(4)); + + /** + * ["LRUCache","put","put","put","put","get","get"] + * [[2],[2,1],[1,1],[2,3],[4,1],[1],[2]] + * + */ + LRUCache cache1 = new LRUCache(2); + cache1.put(2, 1); + cache1.put(1, 1); + cache1.put(2, 3); + cache1.put(4, 1); + System.out.println(cache1.get(1)); + System.out.println(cache1.get(2)); + } + + + class LRUCache { + + LinkedHashMap map = new LinkedHashMap<>(); // 有序 + int defaultSize = 0 ; + public LRUCache(int capacity) { + defaultSize = capacity; + } + + public int get(int key) { + if (map.containsKey(key)) { + Integer v = map.get(key); + map.remove(key); + map.put(key, v); + return v; + } + return -1; + } + + public void put(int key, int value) { + + if (map.containsKey(key)) { + map.put(key, value); + get(key); + return; + } + + map.put(key, value); + if (map.size() > defaultSize) { + for (Integer i : map.keySet()) { + map.remove(i); + break; + } + } + } + } + +} diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode15.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode15.java index c98b1a6..2314534 100644 --- a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode15.java +++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode15.java @@ -1,5 +1,7 @@ package cn.whaifree.redo.redo_all_240721; +import org.junit.Test; + import java.util.ArrayList; import java.util.Arrays; import java.util.List; @@ -31,7 +33,7 @@ public class LeetCode15 { int mid = left + 1; int right = len - 1; if (left > 0 && nums[left] == nums[left - 1]) { - break; + continue; } while (mid < right) { int sum = nums[left] + nums[mid] + nums[right]; @@ -55,4 +57,53 @@ public class LeetCode15 { } return res; } + + @Test + public void test() { + System.out.println(new Solution().threeSum(new int[]{-1,0,1,2,-1,-4,-2,-3,3,0,4})); + } + + + class Solution { + List> res = null; + public List> threeSum(int[] nums) { + res = new ArrayList<>(); + threeSum(nums, 0); + return res; + } + + public void threeSum(int[] nums, int sum) { + Arrays.sort(nums); + int left = 0; + + while (left < nums.length - 2) { + int right = nums.length - 1; + if (left > 0 && nums[left] == nums[left - 1]) { + left++; + continue; + } + int mid = left + 1; + while (mid < right) { + int nowSum = nums[left] + nums[mid] + nums[right]; + if (nowSum == sum) { + res.add(Arrays.asList(nums[left], nums[mid], nums[right])); + while (mid < right && nums[mid] == nums[mid + 1]) { // mid是往右探头 + mid++; + } + while (mid < right && nums[right] == nums[right - 1]) { // right是往左探头 + right--; + } + mid++; + right--; + } else if (nowSum > sum) { + right--; + } else { + mid++; + } + } + + left++; + } + } + } } diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode5.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode5.java new file mode 100644 index 0000000..d94b525 --- /dev/null +++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode5.java @@ -0,0 +1,43 @@ +package cn.whaifree.redo.redo_all_240721; + +import org.junit.Test; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/9/16 15:29 + * @注释 + */ +public class LeetCode5 { + @Test + public void test() + { + System.out.println(new Solution().longestPalindrome("babad")); + } + + class Solution { + public String longestPalindrome(String s) { + String maxHuiWen = ""; + for (int i = 0; i < s.length(); i++) { + String huiWenA = getHuiWen(s, i, i); + String huiWenB = getHuiWen(s, i, i + 1); + if (huiWenA.length() > maxHuiWen.length()) { + maxHuiWen = huiWenA; + } + if (huiWenB.length() > maxHuiWen.length()) { + maxHuiWen = huiWenB; + } + } + return maxHuiWen; + } + + + public String getHuiWen(String s, int start, int end) { + while (start >= 0 && end < s.length() &&s.charAt(start) == s.charAt(end)) { + start--; + end++; + } + return s.substring(start + 1, end); + } + } +} diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode53.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode53.java index 6e98b13..45cf814 100644 --- a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode53.java +++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode53.java @@ -2,6 +2,8 @@ package cn.whaifree.redo.redo_all_240721; import org.junit.Test; +import java.util.Arrays; + /** * @version 1.0 * @Author whai文海 @@ -72,4 +74,34 @@ public class LeetCode53 { return max; } } + + @Test + public void test2() + { + int[] nums = new int[]{-2,1,-3,4,-1,2,1,-5,4}; + Solution2 solution = new Solution2(); + System.out.println(solution.maxSubArray(nums)); + } + + class Solution2 { + /** + * dp[i] 表述i位置的最大子数组的和 + * @param nums + * @return + */ + public int maxSubArray(int[] nums) { + int[] dp = new int[nums.length]; + dp[0] = nums[0]; + for (int i = 1; i < nums.length; i++) { + if (dp[i - 1] > 0 && dp[i - 1] + nums[i] > 0) { + // 不要拖后腿 + dp[i] = dp[i - 1] + nums[i]; + } else { + dp[i] = nums[i]; + } + } + return Arrays.stream(dp).max().getAsInt(); + } + + } }