上海交通大学计算机考研复试 2018年(java)

问题一：
求n的阶乘末尾连续0的个数

import java.util.*;
import java.io.*;
import java.text.* ;
import java.math.*;
public class Main
{
    public static void main(String[] args){
    	try {
	        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
	        int n = Integer.parseInt(br.readLine());
	        int res = 0;
	        while(n > 0) {
	        	res += n/5;
	        	n /= 5;
	        }
	        System.out.println(res);
 	    } catch (IOException e) {
	        e.printStackTrace();
	    }
    }
}

问题二：
求两序列的最长公共子串，要求不包含数字

import java.util.*;
import java.io.*;
import java.text.* ;
import java.math.*;
public class Main
{
	static ArrayList<String> res = new ArrayList<>();
    public static void main(String[] args){
    	try {
	        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
	        char[] ch1 = br.readLine().toCharArray();
	        char[] ch2 = br.readLine().toCharArray();
	        int n1 = ch1.length;
	        int n2 = ch2.length;
	        int[][] dp = new int[n1+1][n2+1];
	        for(int i = 1; i <= n1; i++) {
	        	for(int j = 1; j <= n2; j++) {
	        		if(ch1[i-1] == ch2[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
	        		else dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]);
	        	}
	        }
	        getStr(dp, ch1, ch2, n1, n2, "");
	        for(int i = 0; i < res.size(); i++) {
	        	System.out.println(res.get(i));
	        }
 	    } catch (IOException e) {
	        e.printStackTrace();
	    }
    }
    public static void getStr(int[][] dp, char[] ch1, char[] ch2, int i, int j, String s) {
    	if(i == 0 || j == 0) {
    		res.add(s);
    		return;
    	}
    	if(ch1[i-1] == ch2[j-1]) {
    		getStr(dp, ch1, ch2, i-1, j-1, ch1[i-1]+s);
    	}
    	else if(dp[i-1][j] == dp[i][j-1]) {
    		getStr(dp, ch1, ch2, i-1, j, s);
    		getStr(dp, ch1, ch2, i, j-1, s);
    	}
    	else if(dp[i-1][j] > dp[i][j-1]) getStr(dp, ch1, ch2, i-1, j, s);
    	else getStr(dp, ch1, ch2, i, j-1, s);
    }
}