public int dayOfYear(String date) {// format YYYY-MM-DDint year = Integer.parseInt(date.substring(0, 4));int month = Integer.parseInt(date.substring(5, 7));int day = Integer.parseInt(date.substring(8));int[] daysOfMonthList = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};// 闰月if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {daysOfMonthList[1]++;}int daysBeforeThisMonth = 0;if (month > 1){for (int i = 0; i < month - 1; i++) {daysBeforeThisMonth += daysOfMonthList[i];}}return day+daysBeforeThisMonth;
}

class Solution {public boolean isPalindrome(String s) {int n = s.length();int left = 0;int right = n-1;while(left < right){while(left < right && !Character.isLetterOrDigit(s.charAt(left))){left++;}while(left < right && !Character.isLetterOrDigit(s.charAt(right))){right--;}if(Character.toLowerCase(s.charAt(left)) != Character.toLowerCase(s.charAt(right))){return false;}left++;right--;}return true;}
}

class Solution {public void reverseString(char[] s) {// 双指针int left = 0;int right = s.length-1;while(left < right){char temp = s[left];s[left] = s[right];s[right] = temp;left++;right--;}}
}

class Solution {public boolean isValid(String s) {// map {} 栈// checkif(s.isEmpty()){return true;}Map<Character,Character> map = new HashMap();map.put(']','[');map.put('}','{');map.put(')','(');Stack<Character> stack = new Stack();for(Character c: s.toCharArray()){if(map.containsKey(c)){// 说明有括号Character topElement = stack.isEmpty()?'#':stack.pop();if(map.get(c) != topElement){return false;}}else{stack.push(c);}}return stack.isEmpty();}
}

class Solution {public boolean isSubsequence(String s, String t) {// 贪心 双指针int n = s.length();int m = t.length();int i =0, j=0;while(i<n && j<m){if(s.charAt(i) == t.charAt(j)){i++;}j++;}return i == n;}
}

class Solution {public int longestPalindrome(String s) {// hash 偶数++ 奇数放中间只能1个Map<Character,Integer> counter = new HashMap();for( int i = 0; i< s.length(); i++){counter.merge(s.charAt(i),1,(a,b)->(a+b));}// 统计构造回文串的最大长度int res = 0, odd = 0 ;for(Map.Entry<Character,Integer> kv: counter.entrySet()){// 当前字符出现次数向下取偶数，并计入resint count = kv.getValue();int rem = count % 2;res += count - rem;// 如果当前字符出现次数是奇数，将odd置位1if(rem == 1){odd = 1;}}return res+odd;}
}

class Solution {public boolean buddyStrings(String s, String goal) {//check lenif (s.length() != goal.length()){return false;}// equalif (s.equals(goal)){int[] count = new int[26];for (int i = 0; i < s.length(); i++) {int assicCount = s.charAt(i)-'a';count[assicCount]++;//对应字母的频率if (count[assicCount] > 1){// 有重复，只要换重复的就一定相等return true;}}return false;}else {// first secondint first = -1;int second = -1;for (int i = 0; i < s.length(); i++) {// 只能有两个相同位置的字符不一样if (s.charAt(i) != goal.charAt(i)){if (first==-1){first = i;}else if (second==-1){second = i;}else {// 超过两个return false;}}}return (second != -1 && s.charAt(first) == goal.charAt(second) && s.charAt(second) == goal.charAt(first));}}
}

class Solution {public String longestCommonPrefix(String[] strs) {// checkif(strs.length ==0){return "";}// 先排序 再比较头尾Arrays.sort(strs);int n = strs.length;String ans = "";for(int i = 0; i< strs[0].length();i++){if(strs[0].charAt(i) == strs[n-1].charAt(i)){ans += strs[0].charAt(i);}else{break;}}return ans;}
}

class Solution {public String reformatNumber(String number) {StringBuilder digits = new StringBuilder();for(int i = 0; i < number.length(); i++){char c = number.charAt(i);if(Character.isDigit(c)){digits.append(c);}}int n = digits.length();int currPt = 0;StringBuilder ans = new StringBuilder();while(n > 0){if(n > 4){ans.append(digits.substring(currPt,currPt+3)+"-");n -=3;currPt += 3;}else{if(n==4){ans.append(digits.substring(currPt,currPt+2)+"-"+digits.substring(currPt+2,currPt+4));}else {ans.append(digits.substring(currPt,currPt+n));}break;}}return ans.toString();}
}

class Solution {public boolean checkRecord(String s) {return s.indexOf('A') == s.lastIndexOf('A') && !s.contains("LLL");}
}

class Solution {public int[] twoSum(int[] nums, int target) {// cacheMap<Integer,Integer> cache = new HashMap();for(int i=0;i<nums.length;i++){if(cache.containsKey(target-nums[i])){return new int[]{cache.get(target-nums[i]),i};}cache.put(nums[i],i);}return new int[]{};}
}

class Solution {public int majorityElement(int[] nums) {// checkif(nums.length <=2){return nums[nums.length-1];}// 排序后中间元素Arrays.sort(nums);return nums[nums.length/2];}
}

class Solution {public int maxSubArray(int[] nums) {//checkif(nums == null || nums.length==0){return 0;}int maxCurrent = nums[0]; // 当前元素的子数组和int maxGlobal = nums[0]; // 全局最大子数组和for(int i=1;i<nums.length;i++){// 人生的每个阶段，如果前一个阶段是负积累，及时抛弃，开启新篇章，否则持续积累// 选择当前元素作为新子数组的开始，或者将其添加到前一个元素的子数组中maxCurrent = Math.max(nums[i],maxCurrent+nums[i]);// 每个阶段都要做下总结，是否全局最优// 更新全局最大子数组和maxGlobal = Math.max(maxGlobal,maxCurrent);}return maxGlobal;}
}

class Solution {public boolean canMakeArithmeticProgression(int[] arr) {if(arr.length ==2){return true;}Arrays.sort(arr);int res = arr[1]-arr[0];for(int i=2;i<arr.length;i++){if((arr[i]-arr[i-1]) != res){return false;}}return true;}
}

class Solution {public void merge(int[] nums1, int m, int[] nums2, int n) {// 双指针int[] newNums = new int[m+n];int i = 0;int j = 0;int p = 0;while(i<m && j<n){if(nums1[i]<nums2[j]){newNums[p] = nums1[i];p++;i++;}else{newNums[p] = nums2[j];p++;j++;}}if(i<m){// 复制从i到m的元素过去System.arraycopy(nums1,i,newNums,p,m-i);}if(j<n){System.arraycopy(nums2,j,newNums,p,n-j);}// 拷贝到nums1System.arraycopy(newNums,0,nums1,0,m+n);}
}

class Solution {public int findLHS(int[] nums) {Map<Integer,Integer> map = new HashMap();for(int i = 0;i < nums.length;i++){map.put(nums[i],map.getOrDefault(nums[i],0)+1);}int ans = 0;for(int i: map.keySet()){if(map.containsKey(i-1)){ans = Math.max(ans,map.get(i)+map.get(i-1));}}return ans;}
}

class Solution {public double findMaxAverage(int[] nums, int k) {int sum = 0;int n = nums.length;for(int i=0;i<k;i++){sum += nums[i];}int maxSum = sum;for(int i=k;i<n;i++){sum = sum - nums[i-k] + nums[i];maxSum = Math.max(maxSum, sum);}return maxSum * 1.0/k;}
}

class Solution {public int islandPerimeter(int[][] grid) {int perimeter = 0;int rows = grid.length;int cols = grid[0].length;for(int i=0;i<rows;i++){for(int j = 0; j< cols;j++){// 四个位置，水 或者 越界 再++if(grid[i][j] == 1){// 上方if(i==0 || grid[i-1][j] == 0){perimeter++;}// 下方if(i==rows-1 || grid[i+1][j]==0){perimeter++;}// 左侧if(j==0|| grid[i][j-1]==0){perimeter++;}// 右侧if(j==cols-1 || grid[i][j+1]==0){perimeter++;}}}}return perimeter;}
}

class Solution {public boolean isPalindrome(ListNode head) {if(head.next == null){return true;}// stackDeque<ListNode> stack = new ArrayDeque();ListNode newHead = head;while(head!=null){stack.push(head);head = head.next;}while(newHead != null){if(newHead.val != stack.pop().val){return false;}newHead = newHead.next;}return true;}
}

class Solution {public ListNode mergeTwoLists(ListNode list1, ListNode list2) {ListNode dummy = new ListNode(-1);ListNode head = dummy;while(list1!=null && list2!=null){if(list1.val>list2.val){head.next = list2;head = head.next;list2 = list2.next;}else{head.next = list1;head = head.next;list1 = list1.next;}}while(list1!=null){head.next = list1;head = head.next;list1 = list1.next;}while(list2!=null){head.next = list2;head = head.next;list2 = list2.next;}return dummy.next;}
}

public class Solution {public boolean hasCycle(ListNode head) {// checkif(head == null){return false;}// 双指针ListNode fast = head;ListNode slow = head;while(fast.next != null && fast.next.next!= null){fast = fast.next.next;slow = slow.next;if(fast == slow ){return true;}}return false;}
}

class Solution {public ListNode deleteDuplicates(ListNode head) {if(head == null){return head;}ListNode cur = head;while(cur.next != null){if(cur.val == cur.next.val){cur.next = cur.next.next;}else{cur = cur.next;}}return head;}
}

class Solution {public String validIPAddress(String queryIP) {if (queryIP.indexOf(".") >= 0) {return isIPv4(queryIP) ? "IPv4" : "Neither";} else {return isIPv6(queryIP) ? "IPv6" : "Neither";}}private boolean isIPv4(String queryIP) {// 加-1防止出现空字符串无法计数 如192.168.1.1，后面多了个点，不加-1会被忽略后面的空串String[] split = queryIP.split("\\.",-1);//个数不是4个if (split.length != 4) {return false;}for (String s : split) {// 每个长度不在1-3之间if (s.length() > 3 || s.length() == 0) {return false;}// 有前导0 并且长度不为1if (s.charAt(0) == '0' && s.length() != 1) {return false;}// 计算数字int ans = 0;for (int j = 0; j < s.length(); j++) {char c = s.charAt(j);if (!Character.isDigit(c)) {return false;}ans = ans * 10 +(c - '0');}//数字超过255if (ans > 255) {return false;}}return true;}public boolean isIPv6(String queryIP) {String[] split = queryIP.split(":", -1);//数量不是8if (split.length != 8) {return false;}for (String s : split) {// 每个串 长度不是1-4之间if (s.length() > 4 || s.length() == 0) {return false;}for (int i = 0; i < s.length(); i++) {char c = s.charAt(i);//不是数字且字母不在a-f之间if (!Character.isDigit(c) && !('a' <= Character.toLowerCase(c) && Character.toLowerCase(c) <= 'f')) {return false;}}}return true;}
}

正则太难了…

class Solution {public List<String> topKFrequent(String[] words, int k) {Map<String, Integer> frequencyMap = new HashMap<>();for (String word : words) {frequencyMap.put(word, frequencyMap.getOrDefault(word, 0) + 1);}// 小顶堆PriorityQueue<WordFrequency> minHeap = new PriorityQueue<>();for (Map.Entry<String, Integer> entry : frequencyMap.entrySet()) {minHeap.offer(new WordFrequency(entry.getKey(), entry.getValue()));if (minHeap.size() > k) {minHeap.poll();}}List<String> result = new ArrayList<>();while (!minHeap.isEmpty()) {result.add(minHeap.poll().word);}Collections.reverse(result);return result;}public static class WordFrequency implements Comparable<WordFrequency> {String word;int frequency;public WordFrequency(String word, int frequency) {this.word = word;this.frequency = frequency;}@Overridepublic int compareTo(WordFrequency wordFrequency) {if (this.frequency != wordFrequency.frequency) {return Integer.compare(this.frequency, wordFrequency.frequency);} else {return wordFrequency.word.compareTo(this.word);}}}
}