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加油冲

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Zerroi 2024-03-14 20:58:23 +08:00
parent 39cb705c71
commit a01e34bcfb
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36
com/zerroi/leetcode/Three11/LengthOfLastWord.java Normal file
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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;
}
}

40
com/zerroi/leetcode/Three11/RomanToInt.java Normal file
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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<Character, Integer> 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;
}
}

40
com/zerroi/leetcode/Three12/IsSubsequence.java Normal file
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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();
}
}

38
com/zerroi/leetcode/Three12/MaxArea.java Normal file
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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;
}
}

51
com/zerroi/leetcode/Three12/TwoSum.java Normal file
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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;
}
}

37
com/zerroi/leetcode/Three13/MinSubArrayLen.java Normal file
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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;
}
}

52
com/zerroi/leetcode/Three13/ThreeSum.java Normal file
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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<List<Integer>> 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<List<Integer>> threeSum(int[] nums) {
Arrays.sort(nums);
List<List<Integer>> 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;
}
}

23
com/zerroi/leetcode/Three14/LongestCommonPrefix.java Normal file
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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;
}
}

34
com/zerroi/leetcode/Three14/ReverseWords.java Normal file
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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();
}
}

1
com/zerroi/leetcode/ThreeTen/IsPalindrome.java
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@ -53,5 +53,6 @@ class SolutionSecond {
return ans;
}
}
return false;
}
}