diff --git a/com/zerroi/leetcode/Three11/LengthOfLastWord.java b/com/zerroi/leetcode/Three11/LengthOfLastWord.java new file mode 100644 index 0000000..ff7c901 --- /dev/null +++ b/com/zerroi/leetcode/Three11/LengthOfLastWord.java @@ -0,0 +1,36 @@ +package com.zerroi.leetcode.Three11; + +public class LengthOfLastWord { + public static void main(String[] args) { + SolutionSecond solutionSecond = new SolutionSecond(); +// int res = solutionSecond.lengthOfLastWord(" fly me to the moon "); +// int res = solutionSecond.lengthOfLastWord("Hello World"); + int i = solutionSecond.lengthOfLastWord("a "); + System.out.println("i = " + i); +// System.out.println("res = " + res); + } +} + +/* +* 给你一个字符串 s，由若干单词组成，单词前后用一些空格字符隔开。返回字符串中 最后一个 单词的长度。 + +单词 是指仅由字母组成、不包含任何空格字符的最大 +子字符串 +。*/ +class SolutionSecond { + public int lengthOfLastWord(String s) { + int res = 0; + boolean flag = false; + for (int i = s.length() - 1; i >= 0; i--) { +// 从字符串后面开始遍历，找到第一字母出现的位置开始记录 + if (s.charAt(i) != ' ') { + res++; + flag = true; + } else if (flag) { + return res; + } + } +// System.out.println(s.substring(startIndex, endIndex + 1)); + return res; + } +} diff --git a/com/zerroi/leetcode/Three11/RomanToInt.java b/com/zerroi/leetcode/Three11/RomanToInt.java new file mode 100644 index 0000000..342bcc5 --- /dev/null +++ b/com/zerroi/leetcode/Three11/RomanToInt.java @@ -0,0 +1,40 @@ +package com.zerroi.leetcode.Three11; + +import java.util.HashMap; +import java.util.Map; + +public class RomanToInt { + public static void main(String[] args) { + SolutionFirst solutionFirst = new SolutionFirst(); + int res = solutionFirst.romanToInt("XLVI"); + System.out.println("res = " + res); + } +} + +class SolutionFirst { + public int romanToInt(String s) { + Map map = new HashMap<>(); + map.put('I', 1); + map.put('V', 5); + map.put('X', 10); + map.put('L', 50); + map.put('C', 100); + map.put('D', 500); + map.put('M', 1000); + int res = 0; + for (int i = 0; i < s.length(); i++) { + if (i != s.length() - 1) { + if (map.get(s.charAt(i + 1)) > map.get(s.charAt(i))) { + res += map.get(s.charAt(i + 1)) - map.get(s.charAt(i)); + i++; + } else { + res += map.get(s.charAt(i)); + } + } else { + res += map.get(s.charAt(i)); + } + } + return res; + } +} + diff --git a/com/zerroi/leetcode/Three12/IsSubsequence.java b/com/zerroi/leetcode/Three12/IsSubsequence.java new file mode 100644 index 0000000..b0df291 --- /dev/null +++ b/com/zerroi/leetcode/Three12/IsSubsequence.java @@ -0,0 +1,40 @@ +package com.zerroi.leetcode.Three12; + +public class IsSubsequence { + public static void main(String[] args) { + SolutionFirst solutionFirst = new SolutionFirst(); +// boolean res = solutionFirst.isSubsequence("abc", "ahbgdc"); +// boolean res = solutionFirst.isSubsequence("axc", "ahbgdc"); +// boolean res = solutionFirst.isSubsequence("acb", "ahbgdc"); + boolean res = solutionFirst.isSubsequence("", ""); + System.out.println("res = " + res); + } +} + +/* +* 给定字符串 s 和 t ，判断 s 是否为 t 的子序列。 + +字符串的一个子序列是原始字符串删除一些（也可以不删除）字符而不改变剩余字符相对位置形成的新字符串。（例如，"ace"是"abcde"的一个子序列，而"aec"不是）。 + +进阶： + +如果有大量输入的 S，称作 S1, S2, ... , Sk 其中 k >= 10亿，你需要依次检查它们是否为 T 的子序列。在这种情况下，你会怎样改变代码？ +* */ +class SolutionFirst { + public boolean isSubsequence(String s, String t) { + int n1 = s.length(); + int j = 0; + int count = 0; + for (int i = 0; i < n1; i++) { + while (j < t.length()) { + if (s.charAt(i) == t.charAt(j)) { + count ++; + j++; + break; + } + j++; + } + } + return count == s.length(); + } +} diff --git a/com/zerroi/leetcode/Three12/MaxArea.java b/com/zerroi/leetcode/Three12/MaxArea.java new file mode 100644 index 0000000..19486a2 --- /dev/null +++ b/com/zerroi/leetcode/Three12/MaxArea.java @@ -0,0 +1,38 @@ +package com.zerroi.leetcode.Three12; + +/* +* 给定一个长度为 n 的整数数组 height 。有 n 条垂线，第 i 条线的两个端点是 (i, 0) 和 (i, height[i]) 。 + +找出其中的两条线，使得它们与 x 轴共同构成的容器可以容纳最多的水。 + +返回容器可以储存的最大水量。 + +说明：你不能倾斜容器。 +* */ +public class MaxArea { + public static void main(String[] args) { + Solution solution = new Solution(); + int res = solution.maxArea(new int[]{1, 8, 6, 2, 5, 4, 8, 3, 7}); + System.out.println("res = " + res); + } +} + +class Solution { + public int maxArea(int[] height) { + int left = 0; + int right = height.length - 1; + int res = 0; + while (left < right) { + int h = Math.min(height[left], height[right]); + int width = right - left; + res = Math.max(h * width, res); + while (left < right && height[left] <= h) { + left++; + } + while (left < right && height[right] <= h) { + right--; + } + } + return res; + } +} \ No newline at end of file diff --git a/com/zerroi/leetcode/Three12/TwoSum.java b/com/zerroi/leetcode/Three12/TwoSum.java new file mode 100644 index 0000000..5441055 --- /dev/null +++ b/com/zerroi/leetcode/Three12/TwoSum.java @@ -0,0 +1,51 @@ +package com.zerroi.leetcode.Three12; + +import java.util.Arrays; + +/* +* 给你一个下标从 1 开始的整数数组 numbers ，该数组已按 非递减顺序排列 ，请你从数组中找出满足相加之和等于目标数 target 的两个数。如果设这两个数分别是 numbers[index1] 和 numbers[index2] ，则 1 <= index1 < index2 <= numbers.length 。 + +以长度为 2 的整数数组 [index1, index2] 的形式返回这两个整数的下标 index1 和 index2。 + +你可以假设每个输入 只对应唯一的答案 ，而且你 不可以 重复使用相同的元素。 + +你所设计的解决方案必须只使用常量级的额外空间。 +* */ +public class TwoSum { + public static void main(String[] args) { + SolutionSecond solutionSecond = new SolutionSecond(); + int[] res = solutionSecond.twoSum(new int[]{2, 7, 11, 15}, 9); + for (int i : res) { + System.out.println("i = " + i); + } + } +} + +class SolutionSecond { + public int[] twoSum(int[] numbers, int target) { + for (int i = 0; i < numbers.length; i++) { + for (int j = i + 1; j < numbers.length; j++) { + if (numbers[i] + numbers[j] == target) { + return new int[]{i+1, j+1}; + } + } + } + return null; + } + + public int[] twoSum(int[] numbers, int target, int abc) { + int left = 0; + int right = numbers.length - 1; + while (left < right) { + int sum = numbers[left] + numbers[right]; + if (sum == target) { + return new int[]{left + 1, right + 1}; + } else if (sum > target) { + right--; + } else { + left++; + } + } + return null; + } +} diff --git a/com/zerroi/leetcode/Three13/MinSubArrayLen.java b/com/zerroi/leetcode/Three13/MinSubArrayLen.java new file mode 100644 index 0000000..64fa93a --- /dev/null +++ b/com/zerroi/leetcode/Three13/MinSubArrayLen.java @@ -0,0 +1,37 @@ +package com.zerroi.leetcode.Three13; + +import java.util.Arrays; + +public class MinSubArrayLen { + public static void main(String[] args) { + SolutionSecond solutionSecond = new SolutionSecond(); +// int res = solutionSecond.minSubArrayLen(7, new int[]{2, 3, 1, 2, 4, 3}); + int res = solutionSecond.minSubArrayLen(11, new int[]{1,2,3,4,5}); +// int res = solutionSecond.minSubArrayLen(11, new int[]{1, 1, 1, 1, 1, 1, 1, 1}); + System.out.println("res = " + res); + } +} + +/* +给定一个含有 n 个正整数的数组和一个正整数 target 。 + +找出该数组中满足其总和大于等于 target 的长度最小的 连续 +子数组 + [numsl, numsl+1, ..., numsr-1, numsr] ，并返回其长度。如果不存在符合条件的子数组，返回 0 。 +*/ +class SolutionSecond { + public int minSubArrayLen(int target, int[] nums) { + int sum = 0; + int minLen = Integer.MAX_VALUE; + int index = 0; + for (int i = 0; i < nums.length; i++) { + sum += nums[i]; + while (sum >= target) { + minLen = Math.min(minLen, index - i + 1); + sum -= nums[index]; + index ++; + } + } + return minLen == Integer.MAX_VALUE ? 0 : minLen; + } +} diff --git a/com/zerroi/leetcode/Three13/ThreeSum.java b/com/zerroi/leetcode/Three13/ThreeSum.java new file mode 100644 index 0000000..cd5fc47 --- /dev/null +++ b/com/zerroi/leetcode/Three13/ThreeSum.java @@ -0,0 +1,52 @@ +package com.zerroi.leetcode.Three13; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; + +public class ThreeSum { + public static void main(String[] args) { + SolutionFirst solutionFirst = new SolutionFirst(); + List> res = solutionFirst.threeSum(new int[]{-1,0,1,2,-1,-4}); + res.forEach(System.out::println); + } +} + +/* +* 给你一个整数数组 nums ，判断是否存在三元组 [nums[i], nums[j], nums[k]] 满足 i != j、i != k 且 j != k ，同时还满足 nums[i] + nums[j] + nums[k] == 0 。请 + +你返回所有和为 0 且不重复的三元组。 + +注意：答案中不可以包含重复的三元组。 +* */ +class SolutionFirst { + public List> threeSum(int[] nums) { + Arrays.sort(nums); + List> res = new ArrayList<>(); + for (int i = 0; i < nums.length - 1; i++) { + if (i > 0 &&nums[i] == nums[i - 1]) { + continue; + } + int left = i + 1; + int right = nums.length - 1; + while (left < right ) { + int sum = nums[left] + nums[right] + nums[i]; + if (sum == 0) { + res.add(List.of(nums[left], nums[right], nums[i])); + while (left < right && nums[left] == nums[left + 1]) { + left++; + } + while (left < right && nums[right] == nums[right - 1]) { + right--; + } + left++; + } else if (sum > 0) { + right--; + } else { + left++; + } + } + } + return res; + } +} diff --git a/com/zerroi/leetcode/Three14/LongestCommonPrefix.java b/com/zerroi/leetcode/Three14/LongestCommonPrefix.java new file mode 100644 index 0000000..2e866bb --- /dev/null +++ b/com/zerroi/leetcode/Three14/LongestCommonPrefix.java @@ -0,0 +1,23 @@ +package com.zerroi.leetcode.Three14; + +public class LongestCommonPrefix { + public static void main(String[] args) { + SolutionFirst solutionFirst = new SolutionFirst(); + String res = solutionFirst.longestCommonPrefix(new String[]{"flower", "flow", "flight"}); + System.out.println("res = " + res); + } +} + +class SolutionFirst { + public String longestCommonPrefix(String[] strs) { + if (strs.length == 0) return ""; + String prefix = strs[0]; + for (String str : strs) { + while (!str.startsWith(prefix)) { + if (prefix.length() == 0) return ""; + prefix = prefix.substring(0, prefix.length() - 1); + } + } + return prefix; + } +} diff --git a/com/zerroi/leetcode/Three14/ReverseWords.java b/com/zerroi/leetcode/Three14/ReverseWords.java new file mode 100644 index 0000000..10b23db --- /dev/null +++ b/com/zerroi/leetcode/Three14/ReverseWords.java @@ -0,0 +1,34 @@ +package com.zerroi.leetcode.Three14; + +public class ReverseWords { + public static void main(String[] args) { + SolutionSecond solutionSecond = new SolutionSecond(); + String res = solutionSecond.reverseWords("a good example"); + System.out.println("res = " + res); + } +} + +class SolutionSecond { + public String reverseWords(String s) { + StringBuilder builder = new StringBuilder(); + int startIndex = 0; + int endIndex = s.length() - 1; + for (; startIndex < s.length(); startIndex++) { + if (s.charAt(startIndex) != ' ') break; + } + for (; endIndex >= 0; endIndex--) { + if (s.charAt(endIndex) != ' ') break; + } + int cur = endIndex; + for (; startIndex <= endIndex; endIndex--) { + if (s.charAt(endIndex) == ' ') { + if (s.charAt(endIndex + 1) != ' ') { + builder.append(s, endIndex + 1, cur + 1).append(" "); + } + cur = endIndex - 1; + } + } + builder.append(s, startIndex, cur + 1); + return builder.toString(); + } +} diff --git a/com/zerroi/leetcode/ThreeTen/IsPalindrome.java b/com/zerroi/leetcode/ThreeTen/IsPalindrome.java index 64c0550..416f88c 100644 --- a/com/zerroi/leetcode/ThreeTen/IsPalindrome.java +++ b/com/zerroi/leetcode/ThreeTen/IsPalindrome.java @@ -53,5 +53,6 @@ class SolutionSecond { return ans; } } + return false; } }