華爲機試20141103

1.給定一個字符串，按照字符與‘U’的差的絕對值大小升序排列

import java.util.Scanner;  

public class Main{  
    public static void main(String[] args) {  
        Scanner input = new Scanner(System.in);  
        String inputString = input.nextLine();  
        System.out.println(sort(inputString));  
    }  
  
    public static String sort(String str){  
        char[] ch = str.toCharArray();  

        boolean flag = true;
        for(int i = 0; i < ch.length-1; i++){  
            for(int j = 0; j < ch.length-1-i; j++){  
                int m = ch[j] - 'U';  
                if(m < 0)  
                    m = -m;  
                int n = ch[j+1] - 'U';  
                if(n < 0)  
                    n = -n;  
                if(m > n){  
                    char temp = ch[j];  
                    ch[j] = ch[j+1];  
                    ch[j+1] = temp;
                    flag = false;  
                }  
            }  

            if(flag)
                break;
        }  
        return new String(ch);  
  
    }  
}  

2.刪除字符串中重複次數最少的字符，如abb-->bb aabb-->空串

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.List;
import java.util.ArrayList;
public class RemoveDuplicateLeastChar{
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		String inputString = input.nextLine();
		System.out.println(remove(inputString));
	}

	public static String remove(String str){
		Map<Character, Integer> map = new HashMap<Character, Integer>();
		char [] ch = str.toCharArray();
		for(char c : ch){
			if(map.containsKey(c))
				map.put(c, map.get(c) + 1);
			else
				map.put(c, 1);
		}
		int least = 128;
		Set<Character> set = map.keySet();
		for(Character cha : set) {
			if(map.get(cha) < least)
				least = map.get(cha);
		}
		
		List<Character> list = new ArrayList<Character> ();
		for(Character cha : set) {
			if(map.get(cha) == least){
				for(int j = 0; j< ch.length; j++){
					if(ch[j] == cha)
						list.add(ch[j]);
				}
			}
		}

		StringBuffer sb = new StringBuffer();
		for(char c : ch){
			if(!list.contains(c))
				sb.append(c);
		}
		return sb.toString();
	}
}

3.給出二叉樹中和爲某一值的所有路徑

import java.util.Scanner;
import java.util.ArrayList;
/*
binarytree:
      10
   5     12
 4   7  
*/
class Node{
	int data;
        Node left;
        Node right;
}

public class AllSumTreePath{
	private Node root;

	public void insert(int key){
		Node node = new Node();
		node.data = key;
		if(root == null)
			root = node;
		else{
			Node current = root;
			Node parent = null;
			while(true){
				parent = current;
				if(key <= current.data){
					current = current.left;
					if(current == null){
						parent.left = node;
						return;
					}
				}
				else{
					current = current.right;
					if(current == null){
						parent.right = node;
						return;
					}
				}
			}
		}

	}

	
	public static void main(String[] args) {
		AllSumTreePath tree = new AllSumTreePath();

		Scanner input = new Scanner(System.in);
		int sum = input.nextInt();
		Scanner input1 = new Scanner(System.in);
		String inputString = input1.nextLine();

		String [] strarray = inputString.split(",");

		for(String val : strarray){
			int data = Integer.parseInt(val);
			tree.insert(data);
		}
		// tree.insert(10);
		// tree.insert(5);
		// tree.insert(12);
		// tree.insert(4);
		// tree.insert(7);

		// int sum = 22;
		solution(tree.root, sum, new ArrayList<Integer>());

	}

	public static void solution(Node node, int sum, ArrayList<Integer> path){
		if (node == null)  
			return;  

		path.add(node.data);
		
		if(node.left == null && node.right == null) { 
			int pathNum = 0;
			for(int value : path){
				pathNum = pathNum + value;
			}
			if(pathNum == sum){
				boolean isFirst = true;
				for(int value : path){
					if(isFirst){
						System.out.print(value);
						isFirst = false;
					}else
						System.out.print("," + value);
				}
				System.out.println();
			}
			
		}

		solution(node.left, sum, path);  
		solution(node.right, sum, path);
		path.remove(path.size() - 1);
	}
}