几道算法水题

1.汉诺塔问题：

import java.util.Scanner;


public class Hanoi {
    
    public static void main(String[] args) {
        int n;
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            n = cin.nextInt();
            hanoi(n, 'A', 'C', 'B');
        }
    }
    
    public static void hanoi(int n, char a, char b, char c){
        if(n == 1){
            move(a, b);
            return;
        }
        hanoi(n-1, a, c, b);
        move(a, b);
        hanoi(n-1, c, b, a);
    }
    
    public static void move(char a, char b){
        System.out.println("move " + a + " to " + b);
    }
}

 2.归并排序：

import java.util.Scanner;


public class MergeSort {
    public static int[] a, b;
    public static void main(String[] args) {
        int l;
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            l = cin.nextInt();
            a = new int[l + 1];
            b = new int[l + 1];
            
            for(int i = 1; i <= l; i++){
                a[i] = cin.nextInt();
            }
            ms(1, l);
            for(int i = 1; i <= l; i++){
                System.out.printf("%d ", a[i]);
            }
            System.out.println();
        }
    }
    public static void mergeSort(int l, int m, int r){
        int i = l, j = m + 1, k;
        k = l;
        while(i <= m && j <= r){
            if(a[i] <= a[j])
                b[k++] = a[i++];
            else
                b[k++] = a[j++];
        }
        while(i <= m){
            b[k] = a[i];
            k++; i++;
        }
        while(j <= r){
            b[k] = a[j];
            k++; j++;
        }
        for(k = l; k <= r; k++){
            a[k] = b[k];
        }
    }
    public static void ms(int l, int r){
        if(l < r){
            int m = (l + r) / 2;
            ms(l, m);
            ms(m+1, r);
            mergeSort(l, m, r);
        }
    }
}

 3.求众数：

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;



import sun.misc.Compare;
import sun.misc.Sort;


/**
 * @author Administrator
 *
 */
class Num{
    
    public int value;
    public int count;
    
    public Num() {
        value = 0;
        count = 0;
    }
    public Num(int value, int count) {
        super();
        this.value = value;
        this.count = count;
    }
    
    
    public int getValue() {
        return value;
    }


    public void setValue(int value) {
        this.value = value;
    }


    public int getCount() {
        return count;
    }


    public void setCount(int count) {
        this.count = count;
    }


    public String toString() {
        return "value = " + value + "	count = " + count;
    }
}

public class Zhongshu {
    static int[] num;
    static Num[] ans;
    static{
        ans = new Num[10010];
        for(int i = 0; i < 10010; i++){
            ans[i] = new Num();
        }
    }
    public static void main(String[] args) {
        int N;
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            N = cin.nextInt();
            num = new int[N];
            for(int i = 0; i < N; i++){
                num[i] = cin.nextInt();
            }
            Arrays.sort(num);
            int value = num[0], last = 0, count, k = 0;
            for(int i = 1; i < N; i++){
                if(value != num[i]){
                    count = i - last;
                    ans[k].setCount(count);
                    ans[k].setValue(value);
                    k++;
                    last = i;
                    value = num[i];
                }
            }
            count = N - last;
            ans[k].setCount(count);
            ans[k].setValue(value);
            k++;
//            for(int i = 0; i < k; i++){
//                System.out.println(ans[i]);
//            }

            Arrays.sort(ans, 0, k, new MyComparator());
            for(int i = 0; i < k; i++){
                System.out.println(ans[i]);
            }
        }
        
    }
}


class MyComparator implements Comparator{

    public int compare(Object a, Object b) {
        if(a == null || b == null){
            System.out.println("无奈啊！！！");
        }
        Num o1 = (Num)a;
        Num o2 = (Num)b;
        if(o1.getCount() != o2.getCount())
            return o1.getCount() - o2.getCount();
        else
            return o1.getValue() - o2.getValue();
    }

    
}

 4.约瑟夫环：

import java.util.ArrayList;
import java.util.Scanner;



public class 约瑟夫环 {
    public static ArrayList<Integer>arrayList;
    static{
        arrayList = new ArrayList<Integer>();
    }
    static void init(int n){
        arrayList.clear();
        for(int i = 1; i <= n; i++){
            arrayList.add(i);
        }
    }
    static int work(int ele, int pos){
        if(arrayList.size() == 1)
            return arrayList.get(0);
        else{
            int cur = (pos + ele - 1)%arrayList.size();
            if(cur == 0)
                cur = arrayList.size();
            
            System.out.printf("%d死了
", arrayList.get(cur - 1));
            arrayList.remove(cur - 1);
            //System.out.println(arrayList.size());
            return work(ele, cur%arrayList.size() == 0?
                            arrayList.size() : cur%arrayList.size());
        }
    }
    
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        int m, n;
        while(cin.hasNext()){
            n = cin.nextInt();
            m = cin.nextInt();
            init(n);
            System.out.printf("最后%d活着
", work(m, 1));
        }
    }

}