笔试题解答

/** * @author shishusheng * @date 2018/8/22 23:35 */ import java.util.ArrayList; public class ReverseList { private class ListNode { int val; ListNode next = null; ListNode(int val) { this.val = val; } } ArrayList<Integer> arrayList = new ArrayList<>(); public ArrayList<Integer> printListFromTailToHead(ListNode listNode) { if(listNode != null){ this.printListFromTailToHead(listNode.next); arrayList.add(listNode.val); } return arrayList; } } 

显然是斐波那契数列

/** * @author shishusheng * @date 2018/8/22 23:35 */ import java.util.ArrayList; public class JumpFloor { public int JumpFloorII(int N) { int[] stepArr = new int[N]; stepArr[0] = 1; for (int i = 1; i < N; i++) { for (int j = 0; j < i; j++) { stepArr[i] += stepArr[j]; } stepArr[i]+=1; } return stepArr[N - 1]; } } 

/** * @author shishusheng * @date 2018/8/22 23:35 */ public class JudgeTriAngle { public String judgeTriAngle(int a, int b, int c) { if (a + b > c && b + c > a && c + a > b) { return "成立"; } return "不成立"; } } 

import java.util.ArrayList; import java.util.LinkedList; import java.util.List; /** * @author shishusheng * @date 2018/8/22 23:35 */ public class HourseRun { private class Point { private int x; private int y; private int shortest; public Point() { } public Point(int x, int y) { this.x = x; this.y = y; } public int getX() { return x; } public int getY() { return y; } public int getShortest() { return shortest; } public void addShortest(Point point) { this.shortest = point.getShortest() + 1; } } private static final int MAX_SIZE = 8; private static final int MIN_SIZE = 1; private Point start; private Point end; private List<Point> direction = new ArrayList<>(); private LinkedList<Point> unVisitedPoint = new LinkedList<>(); private int[][] markVisited = new int[9][9]; public HourseRun(Point start, Point end) { this.start = start; this.end = end; init(); } public void init() { direction.add(new Point(2, 1)); //right up horizontal direction.add(new Point(2, -1)); //right down horizontal direction.add(new Point(1, -2)); //right down vertical direction.add(new Point(-1, -2)); //left down vertical direction.add(new Point(-2, -1)); //left down horizontal direction.add(new Point(-2, 1)); //left up horizontal direction.add(new Point(-1, 2)); //left up vertical direction.add(new Point(1, 2)); //right up vertical } private int bfs() { Point current = new Point(); while (!unVisitedPoint.isEmpty()) { current = unVisitedPoint.poll(); markVisited[current.getX()][current.getY()] = 1; if (current.getX() == end.getX() && current.getY() == end.getY()) { break; } for (Point aDirection : direction) { Point next = new Point(current.getX() + aDirection.getX(), current.getY() + aDirection.getY()); next.addShortest(current); if (next.getX() < MIN_SIZE || next.getX() > MAX_SIZE || next.getY() < MIN_SIZE || next.getY() > MAX_SIZE) { continue; } if (markVisited[next.getX()][next.getY()] == 0) { unVisitedPoint.add(next); } } } return current.getShortest(); } public int find() { this.unVisitedPoint.add(start); return bfs(); } }