From 1907ff2e3b8557656224f7ce1f13726c65d904c5 Mon Sep 17 00:00:00 2001 From: xiongraorao Date: Sat, 11 Aug 2018 17:02:40 +0800 Subject: [PATCH] =?UTF-8?q?=E7=BD=91=E6=98=93=E7=AC=94=E8=AF=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../com/raorao/interview/alibaba/Main.java | 89 +++++++++++++++++++ .../com/raorao/interview/netease/q1/Main.java | 14 +++ .../com/raorao/interview/netease/q2/Main.java | 69 ++++++++++++++ .../com/raorao/interview/netease/q3/Main.java | 18 ++++ .../java/althorithm/bintree/LevelOrder.java | 76 ++++++++++++++++ .../java/com/raorao/java/base/StreamTest.java | 8 +- .../com/raorao/leetcode/AssignCookie.java | 30 +++++++ interview/struct/algorithm.md | 5 ++ 8 files changed, 305 insertions(+), 4 deletions(-) create mode 100644 code/src/main/java/com/raorao/interview/alibaba/Main.java create mode 100644 code/src/main/java/com/raorao/interview/netease/q1/Main.java create mode 100644 code/src/main/java/com/raorao/interview/netease/q2/Main.java create mode 100644 code/src/main/java/com/raorao/interview/netease/q3/Main.java create mode 100644 code/src/main/java/com/raorao/java/althorithm/bintree/LevelOrder.java create mode 100644 code/src/main/java/com/raorao/leetcode/AssignCookie.java diff --git a/code/src/main/java/com/raorao/interview/alibaba/Main.java b/code/src/main/java/com/raorao/interview/alibaba/Main.java new file mode 100644 index 00000000..bad7bd37 --- /dev/null +++ b/code/src/main/java/com/raorao/interview/alibaba/Main.java @@ -0,0 +1,89 @@ +package com.raorao.interview.alibaba; + +import java.util.Scanner; + +/** + * 从坐标原点出发，依次经过几个目标点，直到回到原点，问最短路径多少. + * + * @author Xiong Raorao + * @since 2018-08-11-8:28 + */ +public class Main { + + private static int times = 0; + private static int minCost = Integer.MAX_VALUE; + + public static void main(String[] args) { + Scanner scanner = new Scanner(System.in); + + // 初始化 + int N = Integer.parseInt(scanner.nextLine()); + + boolean[] mark = new boolean[N]; + Node[] nodes = new Node[N]; + for (int i = 0; i < N; i++) { + String[] coordinate = scanner.nextLine().split(","); + int x = Integer.parseInt(coordinate[0]); + int y = Integer.parseInt(coordinate[1]); + nodes[i] = new Node(x, y); + } + + route(mark, nodes, -1, N, 0, 0); + System.out.println(minCost); + } + + public static int distance(Node from, Node to) { + return Math.abs(from.x - to.x) + Math.abs(from.y - to.y); + } + + /** + * 求解路径 + * @param mark 标记该点是否走过 + * @param nodes 所有的坐标点 + * @param now 第几个目标点 + * @param N 总目标点数 + * @param step 已经走过的目标点数 + * @param cost 花费路程 + */ + private static void route(boolean[] mark, Node[] nodes, int now, int N, int step, int cost) { + + // 如果step == N 说明所有点一定都走过了 + if (step > N) { + minCost = Math.min(minCost, cost + Math.abs(nodes[now].x) + Math.abs(nodes[now].y)); + return; + } + + if (now >= 0 && mark[now]) { + return; + } + + if (now >= 0) { + mark[now] = true; + } + +// System.out.println(step + ": " + cost); + + for (int i = 0; i < N; i++) { + route(mark, nodes, i, N, step + 1, + cost + (now < 0 ? Math.abs(nodes[i].x) + Math.abs(nodes[i].y) + : distance(nodes[i], nodes[now]))); + } + + if (now >= 0) { + mark[now] = false; + } + } + + private static class Node { + + public int x; + public int y; + + public Node(int x, int y) { + this.x = x; + this.y = y; + } + + } + +} diff --git a/code/src/main/java/com/raorao/interview/netease/q1/Main.java b/code/src/main/java/com/raorao/interview/netease/q1/Main.java new file mode 100644 index 00000000..64bea364 --- /dev/null +++ b/code/src/main/java/com/raorao/interview/netease/q1/Main.java @@ -0,0 +1,14 @@ +package com.raorao.interview.netease.q1; + +/** + * . + * + * @author Xiong Raorao + * @since 2018-08-11-16:03 + */ +public class Main { + + public static void main(String[] args) { + + } +} diff --git a/code/src/main/java/com/raorao/interview/netease/q2/Main.java b/code/src/main/java/com/raorao/interview/netease/q2/Main.java new file mode 100644 index 00000000..bd41e517 --- /dev/null +++ b/code/src/main/java/com/raorao/interview/netease/q2/Main.java @@ -0,0 +1,69 @@ +package com.raorao.interview.netease.q2; + +import java.util.Scanner; + +/** + * 分苹果问题， N堆苹果，从左往右数第x个，求第x个在第几堆里面（堆从1开始算） . + * + * @author Xiong Raorao + * @since 2018-08-11-16:09 + */ +public class Main { + + public static void main(String[] args) { + Scanner scanner = new Scanner(System.in); + int n = Integer.parseInt(scanner.nextLine()); + int[] apples = new int[n]; + String[] temp = scanner.nextLine().split(" "); + for (int i = 0; i < n; i++) { + apples[i] = Integer.parseInt(temp[i]); + } + int m = Integer.parseInt(scanner.nextLine()); + int[] queries = new int[m]; + temp = scanner.nextLine().split(" "); + for (int i = 0; i < m; i++) { + queries[i] = Integer.parseInt(temp[i]); + } + process(apples, n, queries, m); + } + + private static void process(int[] apples, int n, int[] queries, int m) { + int[] acc = new int[n]; + acc[0] = apples[0]; + for (int i = 1; i < n; i++) { + acc[i] = acc[i - 1] + apples[i]; + } + for (int i = 0; i < m; i++) { +// for (int j = 0; j < n; j++) { +// if (queries[i] <= acc[j]) { +// System.out.println(j + 1); +// break; +// } +// } + System.out.println(part(0, n - 1, acc, queries[i]) + 1); + } + } + + private static int part(int left, int right, int[] acc, int query) { + int mid = (left + right) / 2; + if (mid == 0) { + return 0; + } + if(left == right ){ + return left; + } + if ( mid < acc.length && query <= acc[mid] && query <= acc[mid + 1] && query >= acc[mid - 1]) { + return mid; + } + if (query > acc[mid]) { + left = mid + 1; + return part(left, right, acc, query); + } + if (query < acc[mid]) { + right = mid - 1; + return part(left, right, acc, query); + } + return 0; + } + +} diff --git a/code/src/main/java/com/raorao/interview/netease/q3/Main.java b/code/src/main/java/com/raorao/interview/netease/q3/Main.java new file mode 100644 index 00000000..73a404c0 --- /dev/null +++ b/code/src/main/java/com/raorao/interview/netease/q3/Main.java @@ -0,0 +1,18 @@ +package com.raorao.interview.netease.q3; + +/** + * . + * + * @author Xiong Raorao + * @since 2018-08-11-16:27 + */ +public class Main { + + public static void main(String[] args) { + + } + + private static void process() { + + } +} diff --git a/code/src/main/java/com/raorao/java/althorithm/bintree/LevelOrder.java b/code/src/main/java/com/raorao/java/althorithm/bintree/LevelOrder.java new file mode 100644 index 00000000..5ba35af2 --- /dev/null +++ b/code/src/main/java/com/raorao/java/althorithm/bintree/LevelOrder.java @@ -0,0 +1,76 @@ +package com.raorao.java.althorithm.bintree; + +import java.util.ArrayList; +import java.util.LinkedList; +import java.util.List; + +/** + * 二叉树的层次遍历. + * + * 描述：输入一个二叉树的根节点，输出 + * + * @author Xiong Raorao + * @since 2018-08-11-10:50 + */ +public class LevelOrder { + + + public static void main(String[] args) { + TreeNode root = new TreeNode(1); + TreeNode left = new TreeNode(2); + left.left = new TreeNode(4); + root.left = left; + TreeNode right = new TreeNode(3); + right.right = new TreeNode(5); + root.right = right; + + List> ret = levelOrder(root); + ret.stream().forEach(e -> { + e.stream().forEach(f -> System.out.print(f + "\t")); + System.out.println(); + }); + } + + + public static List> levelOrder(TreeNode root) { + List> ret = new ArrayList<>(); + if (root == null) { + return ret; + } + LinkedList queue = new LinkedList<>(); + queue.offer(root); + List level = new ArrayList<>(); + int flag = 0; + while (!queue.isEmpty()) { + TreeNode node = queue.poll(); + System.out.print(node.val + " "); + flag--; + if(flag == 0){ + System.out.println(); + } + if (level.size() > 0) { + ret.add(level); + } + if (node.left != null) { + queue.offer(node.left); + } + if (node.right != null) { + queue.offer(node.right); + } + flag = queue.size(); + + } + return ret; + } + + static class TreeNode { + + int val; + TreeNode left; + TreeNode right; + + TreeNode(int x) { + val = x; + } + } +} diff --git a/code/src/main/java/com/raorao/java/base/StreamTest.java b/code/src/main/java/com/raorao/java/base/StreamTest.java index 343865b3..14638f7d 100644 --- a/code/src/main/java/com/raorao/java/base/StreamTest.java +++ b/code/src/main/java/com/raorao/java/base/StreamTest.java @@ -62,10 +62,10 @@ public class StreamTest { * 和前面 Stream 的第一个、第二个、第 n 个元素组合。从这个意义上说，字符串拼接、数值的 sum、min、max、average 都是特殊的 reduce。 */ // 1. 字符串拼接 - Optional ss = stream.reduce((a, b) -> a + b); - System.out.println(ss.orElse(null)); - //String s2 = stream.reduce("", (a, b) -> a + b + "-"); - //System.out.println(s2); + //Optional ss = stream.reduce((a, b) -> a + b); + //System.out.println(ss.orElse(null)); + String s2 = stream.reduce("", (a, b) -> a + "-" + b ); + System.out.println(s2); // 2. 数值相加 Optional sum = intList.stream().reduce((a, b) -> a + b); diff --git a/code/src/main/java/com/raorao/leetcode/AssignCookie.java b/code/src/main/java/com/raorao/leetcode/AssignCookie.java new file mode 100644 index 00000000..66634312 --- /dev/null +++ b/code/src/main/java/com/raorao/leetcode/AssignCookie.java @@ -0,0 +1,30 @@ +package com.raorao.leetcode; + +import java.util.Arrays; + +/** + * 分配饼干. + * + * @author Xiong Raorao + * @since 2018-08-11-10:05 + */ +public class AssignCookie { + + public static void main(String[] args) { + + } + + private static int process(int[] childrens, int[] cookies) { + Arrays.sort(childrens); + Arrays.sort(cookies); + int child = 0; + int cookie = 0; + while (child < childrens.length && cookie < cookies.length) { + if (childrens[child] <= cookies[child]) { + child++; + } + cookie++; + } + return child; + } +} diff --git a/interview/struct/algorithm.md b/interview/struct/algorithm.md index e69de29b..94d2dd65 100644 --- a/interview/struct/algorithm.md +++ b/interview/struct/algorithm.md @@ -0,0 +1,5 @@ +# 大顶堆和小顶堆 + +比如求10亿个数中的最大的前10个数，时时构建只有10个元素的小顶堆，如果比堆顶小，则不处理；如果比堆顶大，则替换堆顶，然后依次下沉到适当的位置。 + +比如求10亿个数中的最小的前10个数，时时构建只有10个元素的大顶堆，如果比堆顶大，则不处理；如果比堆顶小，则替换堆顶，然后依次下沉到适当的位置。 \ No newline at end of file