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fanxb 2021-04-12 17:55:04 +08:00
parent c7cba88e2d
commit c072dbedc8
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44
5.leetcode/src/com/fanxb/common/Q153.java Normal file
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package com.fanxb.common;
/**
* Created with IntelliJ IDEA
* 寻找旋转排序数组中的最小值
* 地址： https://leetcode-cn.com/problems/find-minimum-in-rotated-sorted-array/
* 思路： 需要找到分界点
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q153 {
public int findMin(int[] nums) {
int l = 0, r = nums.length - 1, mid;
int min = nums[0];
while (l <= r) {
mid = (l + r) / 2;
if (nums[l] == nums[mid]) {
//无法判断l,r所处的位置，l++
if (nums[l] < min) {
min = nums[l];
}
l++;
} else if (nums[l] < nums[mid]) {
//说明两个点肯定都落在了左边的升续端内
if (nums[l] < min) {
min = nums[l];
}
l = mid + 1;
} else {
//说明l肯定在左边区间，mid肯定在右边区间
if (nums[mid] < min) {
min = nums[mid];
}
r = mid - 1;
}
}
return min;
}
public static void main(String[] args) {
System.out.println(new Q153().findMin(new int[]{3, 4, 5, 1, 2}));
}
}

44
5.leetcode/src/com/fanxb/common/Q154.java Normal file
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package com.fanxb.common;
/**
* Created with IntelliJ IDEA
* 寻找旋转排序数组中的最小值 II
* 地址： https://leetcode-cn.com/problems/find-minimum-in-rotated-sorted-array-ii/
* 思路： 部分二分查找法，当知道某一段是有序的时候就能够快速判断出这一段的最小值
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q154 {
public int findMin(int[] nums) {
int l = 0, r = nums.length - 1, mid;
int min = Integer.MAX_VALUE;
while (l <= r) {
mid = (l + r) / 2;
if (nums[l] == nums[mid]) {
//无法判断哪边是有序的
if (nums[l] < min) {
min = nums[mid];
}
l++;
} else if (nums[l] < nums[mid]) {
//左边是有序的,找到了左边的最小值
if (nums[l] < min) {
min = nums[l];
}
l = mid + 1;
} else {
//右边是有续的，找到了右边的最小值
if (nums[mid] < min) {
min = nums[mid];
}
r = mid - 1;
}
}
return min;
}
public static void main(String[] args) {
System.out.println(new Q154().findMin(new int[]{1, 0, 1, 1, 1}));
}
}

69
5.leetcode/src/com/fanxb/common/Q34.java Normal file
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package com.fanxb.common;
import java.util.Arrays;
/**
* Created with IntelliJ IDEA
* x 的平方根
* 地址： https://leetcode-cn.com/problems/sqrtx/
* 思路： 题目要求求解一个数的平方根的整数部分，那就那就相当于找到一个数num,使其满足num*mum==x || num*num&lt;x && (num+1)*(num+1)>x
* 可通过二分查找来进行求解，num的值一定是[0,x]中的一个数
* 1. 首先设定l=0,r=x
* 2. mid=(l+r)/2,temp1=mid*mid,temp2=(mid+1)*(mid+1)
* 3. 如果temp1 == x || (temp1 < x && temp2 > x)满足结果即为mid
* 4. 否则判断temp1>x,如果满足r=mid,重复2
* 5. 否则l=mid,重复2
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q34 {
public int[] searchRange(int[] nums, int target) {
if (nums.length == 0) {
return new int[]{-1, -1};
}
int l = 0, r = nums.length - 1;
if (target < nums[0] || target > nums[r]) {
return new int[]{-1, -1};
}
int mid;
while (true) {
mid = (l + r) / 2;
if (nums[mid] == target) {
break;
} else if (nums[mid + 1] == target) {
mid = mid + 1;
break;
} else if (nums[mid] < target) {
if (nums[mid + 1] > target) {
return new int[]{-1, -1};
}
l = mid;
} else {
r = mid;
}
}
//从mid向两端查找
l = mid;
r = mid;
while (true) {
boolean out = true;
if (l > 0 && nums[l - 1] == target) {
l--;
out = false;
}
if (r < nums.length - 1 && nums[r + 1] == target) {
r++;
out = false;
}
if (out) {
break;
}
}
return new int[]{l, r};
}
public static void main(String[] args) {
System.out.println(Arrays.toString(new Q34().searchRange(new int[]{1, 4}, 4)));
}
}

46
5.leetcode/src/com/fanxb/common/Q4.java Normal file
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package com.fanxb.common;
import java.util.Arrays;
/**
* Created with IntelliJ IDEA
* x 的平方根
* 地址： https://leetcode-cn.com/problems/sqrtx/
* 思路： 双路规避排序查找
*
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q4 {
public double findMedianSortedArrays(int[] nums1, int[] nums2) {
int size = nums1.length + nums2.length;
boolean isDoubleSize = (size & 1) == 0;
if (nums1.length == 0) {
return nums2.length == 1 ? nums2[0] : isDoubleSize ? (nums2[size / 2 - 1] + nums2[size / 2]) / 2.0 : nums2[size / 2];
} else if (nums2.length == 0) {
return nums1.length == 1 ? nums1[0] : isDoubleSize ? (nums1[size / 2 - 1] + nums1[size / 2]) / 2.0 : nums1[size / 2];
}
//二路归并找到中间两个位置的数
int count = 0, i = 0, j = 0, value = 0;
while (count < size / 2) {
if (i == nums1.length) {
value = nums2[j++];
} else if (j == nums2.length) {
value = nums1[i++];
} else if (nums1[i] < nums2[j]) {
value = nums1[i++];
} else {
value = nums2[j++];
}
count++;
}
int value2 = i == nums1.length ? nums2[j] : j == nums2.length ? nums1[i] : Math.min(nums1[i], nums2[j]);
return isDoubleSize ? (value + value2) / 2.0 : value2;
}
public static void main(String[] args) {
System.out.println(new Q4().findMedianSortedArrays(new int[]{2,3,4}, new int[]{1}));
}
}

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5.leetcode/src/com/fanxb/common/Q540.java Normal file
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package com.fanxb.common;
/**
* Created with IntelliJ IDEA
* 寻找旋转排序数组中的最小值 II
* 地址： https://leetcode-cn.com/problems/find-minimum-in-rotated-sorted-array-ii/
* 思路： 观察可以发现当没有异常点时，每个奇数位和偶数位都是一致的，一旦加入异常点会导致从异常点开始奇偶位的数不一直
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q540 {
public int singleNonDuplicate(int[] nums) {
int l = 0, r = nums.length - 1, mid = 0;
while (l < r) {
mid = (l + r) / 2;
if ((mid + 1) % 2 == 0 ? nums[mid] == nums[mid - 1] : nums[mid] == nums[mid + 1]) {
//mid所处的位置，奇数位和偶数位的值一样，说明异常点在mid的后面
l = mid + 1;
} else {
//说明异常点在mid或mid之前
r = mid;
}
}
return nums[l];
}
public static void main(String[] args) {
System.out.println(new Q540().singleNonDuplicate(new int[]{1, 1, 2, 3, 3, 4, 4, 8, 8}));
}
}

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5.leetcode/src/com/fanxb/common/Q69.java Normal file
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package com.fanxb.common;
/**
* Created with IntelliJ IDEA
* x 的平方根
* 地址： https://leetcode-cn.com/problems/sqrtx/
* 思路： 题目要求求解一个数的平方根的整数部分，那就那就相当于找到一个数num,使其满足num*mum==x || num*num&lt;x && (num+1)*(num+1)>x
* 可通过二分查找来进行求解，num的值一定是[0,x]中的一个数
* 1. 首先设定l=0,r=x
* 2. mid=(l+r)/2,temp1=mid*mid,temp2=(mid+1)*(mid+1)
* 3. 如果temp1 == x || (temp1 < x && temp2 > x)满足结果即为mid
* 4. 否则判断temp1>x,如果满足r=mid,重复2
* 5. 否则l=mid,重复2
*
*
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q69 {
public int mySqrt(int x) {
if (x == 0 || x == 1) {
return x;
}
int l = 0, r = x;
long temp1, temp2, mid;
while (true) {
mid = (l + r) / 2;
temp1 = mid * mid;
temp2 = (mid + 1) * (mid + 1);
if (temp1 == x || (temp1 < x && temp2 > x)) {
return (int) mid;
} else if (temp1 > x) {
r = (int) mid;
} else {
l = (int) mid;
}
}
}
public static void main(String[] args) {
System.out.println(new Q69().mySqrt(2147395599));
}
}

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5.leetcode/src/com/fanxb/common/Q81.java Normal file
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package com.fanxb.common;
import java.util.Arrays;
/**
* Created with IntelliJ IDEA
* x 的平方根
* 地址： https://leetcode-cn.com/problems/sqrtx/
* 思路：
*
* @author fanxb
* Date: 2020/6/11 9:56
*/
public class Q81 {
public boolean search(int[] nums, int target) {
if (nums.length == 0) {
return false;
}
int l = 0, r = nums.length - 1;
int mid;
while (l <= r) {
mid = (l + r) / 2;
if (nums[mid] == target) {
return true;
}
if (nums[l] == nums[mid]) {
//无法分辨哪边是有序的
l++;
continue;
}
if (nums[l] < nums[mid]) {
//说明[l,mid]是有序的
if (nums[mid] > target && nums[l] <= target) {
r = mid - 1;
} else {
l = mid + 1;
}
} else {
//说明[mid,r]是有序的
if (nums[mid] < target && nums[r] >= target) {
l = mid + 1;
} else {
r = mid - 1;
}
}
}
return false;
}
public static void main(String[] args) {
System.out.println(new Q81().search(new int[]{1,0,1,1,1}, 0));
}
}

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5.leetcode/src/com/fanxb/common/Sort.java Normal file
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package com.fanxb.common;
import java.util.Arrays;
/**
* 排序
*
* @author fanxb
* @date 2021/4/4
**/
public class Sort {
/**
* 冒泡排序
*
* @author fanxb
* @date 2021/4/4
**/
public static int[] sort1(int[] arr) {
for (int i = 0; i < arr.length - 1; i++) {
for (int j = 0, length = arr.length - 1 - i; j < length; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j + 1];
arr[j + 1] = arr[j];
arr[j] = temp;
}
}
}
return arr;
}
public static void quickSort(int[] arr, int start, int end) {
if (end - start <= 1) {
return;
}
int l = start, r = end, base = arr[start];
while (l < r) {
//右边找到一个小于base的然后交换
while (arr[r] >= base && l < r) {
r--;
}
//左边找到一个大于base的
while (arr[l] <= base && l < r) {
l++;
}
int temp = arr[l];
arr[l] = arr[r];
arr[r] = temp;
}
//交换start和i的位置，使base左边的都小于等于base,右边的都大于等于base
arr[start] = arr[l];
arr[l] = base;
//对l左边和右边的分别进行快拍
quickSort(arr, start, l - 1);
quickSort(arr, l + 1, end);
}
/**
* 插入排序
*
* @author fanxb
* @date 2021/4/4
**/
public static void insertSort(int[] arr) {
for (int i = 0; i < arr.length - 1; i++) {
for (int j = i + 1; j > 0 && arr[j - 1] > arr[j]; j--) {
int temp = arr[j - 1];
arr[j - 1] = arr[j];
arr[j] = temp;
}
}
}
public static void main(String[] args) {
int[] s = {23, 49, 13, 12, 45, 393, 21, 21048, 12};
// System.out.println(Arrays.toString(sort1(s)));
// quickSort(s, 0, s.length - 1);
insertSort(s);
System.out.println(Arrays.toString(s));
}
}