From 2c7460783c5ac166909723f1cee8590717b9974d Mon Sep 17 00:00:00 2001 From: xiongraorao Date: Fri, 31 Aug 2018 21:35:50 +0800 Subject: [PATCH] 8.31 --- .../com/raorao/interview/tencent/Main.java | 42 +++++++++++ .../raorao/leetcode/q172/TrailingZeros.java | 19 +++++ .../com/raorao/leetcode/q204/CountPrime.java | 32 +++++++++ .../leetcode/q217/ContainsDuplicate.java | 29 ++++++++ .../leetcode/q238/ProductExceptSelf.java | 36 ++++++++++ .../raorao/leetcode/q326/PowerOfThree.java | 17 +++++ .../raorao/leetcode/q367/PerfectSquare.java | 22 ++++++ .../com/raorao/leetcode/q462/MinMove.java | 69 +++++++++++++++++++ .../java/com/raorao/leetcode/q504/Base7.java | 44 ++++++++++++ interview/note.md | 3 + 10 files changed, 313 insertions(+) create mode 100644 code/src/main/java/com/raorao/interview/tencent/Main.java create mode 100644 code/src/main/java/com/raorao/leetcode/q172/TrailingZeros.java create mode 100644 code/src/main/java/com/raorao/leetcode/q204/CountPrime.java create mode 100644 code/src/main/java/com/raorao/leetcode/q217/ContainsDuplicate.java create mode 100644 code/src/main/java/com/raorao/leetcode/q238/ProductExceptSelf.java create mode 100644 code/src/main/java/com/raorao/leetcode/q326/PowerOfThree.java create mode 100644 code/src/main/java/com/raorao/leetcode/q367/PerfectSquare.java create mode 100644 code/src/main/java/com/raorao/leetcode/q462/MinMove.java create mode 100644 code/src/main/java/com/raorao/leetcode/q504/Base7.java diff --git a/code/src/main/java/com/raorao/interview/tencent/Main.java b/code/src/main/java/com/raorao/interview/tencent/Main.java new file mode 100644 index 00000000..998ef0a7 --- /dev/null +++ b/code/src/main/java/com/raorao/interview/tencent/Main.java @@ -0,0 +1,42 @@ +package com.raorao.interview.tencent; + +import java.util.Scanner; + +/** + * 8.31 模拟题. + * + * @author Xiong Raorao + * @since 2018-08-31-20:52 + */ +public class Main { + + public static void main(String[] args) { + Scanner scanner = new Scanner(System.in); + int k = scanner.nextInt(); + int a = scanner.nextInt(); + int b = scanner.nextInt(); + int x =scanner.nextInt(); + int y = scanner.nextInt(); + System.out.println(process(k,a,b,x,y)); + } + + private static long process(int k, int a, int b, int x, int y) { + long ans = 0; + int mod = 1000000007; + int[][] c = new int[105][105]; + c[0][0] = 1; + for (int i = 1; i <= 100; i++) { + c[i][0] = 1; + for (int j = 1; j <= 100; j++) { + c[i][j] = (c[i - 1][j - 1] + c[i - 1][j]) % mod; + } + } + + for (int i = 0; i <= x; i++) { + if (i * a <= k && (k - a * i) % b == 0 && (-a * i) / b <= y) { + ans = (ans + (c[x][i] * c[y][(k - a * i) / b]) % mod) % mod; + } + } + return ans; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q172/TrailingZeros.java b/code/src/main/java/com/raorao/leetcode/q172/TrailingZeros.java new file mode 100644 index 00000000..56e1cdd0 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q172/TrailingZeros.java @@ -0,0 +1,19 @@ +package com.raorao.leetcode.q172; + +/** + * . + * + * @author Xiong Raorao + * @since 2018-08-31-12:49 + */ +public class TrailingZeros { + + public static void main(String[] args) { + int res = trailingZeroes(10); + System.out.println(res); + } + + public static int trailingZeroes(int n) { + return n == 0 ? 0 : n / 5 + trailingZeroes(n / 5); + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q204/CountPrime.java b/code/src/main/java/com/raorao/leetcode/q204/CountPrime.java new file mode 100644 index 00000000..22c214cb --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q204/CountPrime.java @@ -0,0 +1,32 @@ +package com.raorao.leetcode.q204; + +/** + * 统计素数的数量. + * + * @author Xiong Raorao + * @since 2018-08-31-11:33 + */ +public class CountPrime { + + public static void main(String[] args) { + CountPrime prime = new CountPrime(); + int res = prime.countPrimes(10); + System.out.println(res); + } + + public int countPrimes(int n) { + boolean[] notPrimes = new boolean[n + 1]; + int count = 0; + for (int i = 2; i < n; i++) { + if (notPrimes[i]) { + continue; + } + count++; + // 从 i * i 开始，因为如果 k < i，那么 k * i 在之前就已经被去除过了 + for (long j = (long) (i) * i; j < n; j += i) { + notPrimes[(int) j] = true; + } + } + return count; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q217/ContainsDuplicate.java b/code/src/main/java/com/raorao/leetcode/q217/ContainsDuplicate.java new file mode 100644 index 00000000..39c829f7 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q217/ContainsDuplicate.java @@ -0,0 +1,29 @@ +package com.raorao.leetcode.q217; + +import java.util.HashMap; +import java.util.Map; + +/** + * 判断是否存在重复元素. + * + * @author Xiong Raorao + * @since 2018-08-31-10:31 + */ +public class ContainsDuplicate { + + public static void main(String[] args) { + + } + + public boolean containsDuplicate(int[] nums) { + Map map = new HashMap<>(); + for (int i : nums) { + if (map.containsKey(i)) { + return true; + } else { + map.put(i, 1); + } + } + return false; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q238/ProductExceptSelf.java b/code/src/main/java/com/raorao/leetcode/q238/ProductExceptSelf.java new file mode 100644 index 00000000..ea9c3e6d --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q238/ProductExceptSelf.java @@ -0,0 +1,36 @@ +package com.raorao.leetcode.q238; + +import java.util.Arrays; + +/** + * 除自身以外数组的乘积. + * + * @author Xiong Raorao + * @since 2018-08-31-16:16 + */ +public class ProductExceptSelf { + + public static void main(String[] args) { + int[] input = new int[]{1,2,3,4}; + ProductExceptSelf self = new ProductExceptSelf(); + int[] res = self.productExceptSelf(input); + System.out.println(Arrays.toString(res)); + } + + public int[] productExceptSelf(int[] nums) { + int n = nums.length; + int[] products = new int[n]; + Arrays.fill(products, 1); + int left = 1; + for (int i = 1; i < n; i++) { + left *= nums[i - 1]; + products[i] *= left; + } + int right = 1; + for (int i = n - 2; i >= 0; i--) { + right *= nums[i + 1]; + products[i] *= right; + } + return products; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q326/PowerOfThree.java b/code/src/main/java/com/raorao/leetcode/q326/PowerOfThree.java new file mode 100644 index 00000000..f8142ed0 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q326/PowerOfThree.java @@ -0,0 +1,17 @@ +package com.raorao.leetcode.q326; + +/** + * 判断一个数是否是3的幂. + * + * @author Xiong Raorao + * @since 2018-08-31-16:11 + */ +public class PowerOfThree { + + public boolean isPowerOfThree(int n) { + while (n >= 3 && n % 3 == 0) { + n = n / 3; + } + return n == 1; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q367/PerfectSquare.java b/code/src/main/java/com/raorao/leetcode/q367/PerfectSquare.java new file mode 100644 index 00000000..f8d69bd6 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q367/PerfectSquare.java @@ -0,0 +1,22 @@ +package com.raorao.leetcode.q367; + +/** + * 判断有效的完全平方数. + * + * @author Xiong Raorao + * @since 2018-08-31-16:04 + */ +public class PerfectSquare { + + /** + * 利用平方数的差为等差数列的性质来计算 + */ + public boolean isPerfectSquare(int num) { + int sub = 1; + while (num > 0) { + num -= sub; + sub += 2; + } + return num == 0; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q462/MinMove.java b/code/src/main/java/com/raorao/leetcode/q462/MinMove.java new file mode 100644 index 00000000..ab05ceeb --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q462/MinMove.java @@ -0,0 +1,69 @@ +package com.raorao.leetcode.q462; + +/** + * 改变数组元素使所有的数组元素都相等，求最少的总移动次数. + * + * 思路：找出中位数，可以采用排序，然后计算，也可以采用找中位数的方法来计算 + * + * @author Xiong Raorao + * @since 2018-08-31-15:22 + */ +public class MinMove { + + public static void main(String[] args) { + int[] input = new int[]{1,2,3}; + int res = new MinMove().minMoves2(input); + System.out.println(res); + } + + public int minMoves2(int[] nums) { + int median = getMedian(nums); + int count = 0; + for (int num : nums) { + count += Math.abs(num - median); + } + return count; + } + + private int getMedian(int[] nums) { + int low = 0; + int high = nums.length - 1; + while (low < high) { + int m = partition(nums, low, high); + if (m == nums.length / 2) { + break; + } + if (m < nums.length / 2) { + low = m + 1; + } else { + high = m - 1; + } + } + return nums[nums.length / 2]; + } + + private int partition(int[] nums, int low, int high) { + int i = low; + int j = high + 1; + while (true) { + while (nums[++i] < nums[low] && i < high) { + ; + } + while (nums[--j] > nums[low] && j > low) { + ; + } + if (i >= j) { + break; + } + swap(nums, i, j); + } + swap(nums, low, j); + return j; + } + + private void swap(int[] nums, int i, int j) { + int temp = nums[i]; + nums[i] = nums[j]; + nums[j] = temp; + } +} diff --git a/code/src/main/java/com/raorao/leetcode/q504/Base7.java b/code/src/main/java/com/raorao/leetcode/q504/Base7.java new file mode 100644 index 00000000..d60ea319 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/q504/Base7.java @@ -0,0 +1,44 @@ +package com.raorao.leetcode.q504; + + +/** + * 10进制转7进制. + * + * @author Xiong Raorao + * @since 2018-08-31-11:54 + */ +public class Base7 { + + public static void main(String[] args) { + Base7 base7 = new Base7(); + String res = base7.convertToBase7(100); + System.out.println(res); + } + + public String convertToBase7(int num) { + StringBuilder sb = new StringBuilder(); + convertBase(sb, num); + if (num < 0) { + sb.append("-"); + } + return sb.reverse().toString(); + } + + private void convertBase(StringBuilder sb, int num) { + num = Math.abs(num); + if (num == 0) { + sb.append(0); + return; + } + int a = num / 7; + int b = num % 7; + sb.append(b); + if (a >= 7) { + convertBase(sb, a); + } else if( a > 0) { + sb.append(a); + } + } + + +} diff --git a/interview/note.md b/interview/note.md index ac3b11fd..87641d5e 100644 --- a/interview/note.md +++ b/interview/note.md @@ -47,6 +47,9 @@ Intel | 8.23 | 8.23(新投递) | 电面 | 8.24一面 唯品会 | | 8.30（实时计算工程师） | 珍爱网 | | 8.30(新投递) | 寒武纪 | 8.30 | 8.30(新投递) | +商汤 | 8.31 | 8.31(新投递) | +Keep | 8.31 | 8.31(新投递) +小红书 | 8.31 | 8.31(新投递) # 2 复习内容