8.31

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;
+  }
+}

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);
+  }
+}

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;
+  }
+}

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<Integer, Integer> map = new HashMap<>();
+    for (int i : nums) {
+      if (map.containsKey(i)) {
+        return true;
+      } else {
+        map.put(i, 1);
+      }
+    }
+    return false;
+  }
+}

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;
+  }
+}

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;
+  }
+}

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;
+  }
+}

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;
+  }
+}

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);
+    }
+  }
+
+
+}

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