题目

www.nowcoder.com/practice/de044e89123f4a7482bd2b214a685201?tpId=37&tqId=21231&rp=1&ru=/exam/oj/ta&qru=/exam/oj/ta&sourceUrl=%2Fexam%2Foj%2Fta%3FtpId%3D37&difficulty=undefined&judgeStatus=undefined&tags=&title=

参考题解

import java.util.*;
import java.io.*;
public class Main {
  public static void main(String[] args) throws IOException {
        StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        st.nextToken();          // 分隔符
        int n = (int) st.nval;   // 强转
        int[] arr = new int[11111112];
 
        for (int i = 0; i < n; i++) {
            st.nextToken();
            int key = (int) st.nval;
            st.nextToken();
            int value = (int) st.nval;
            arr[key] = arr[key] + value;
        }
 
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < arr.length ; i++) {
            if(arr[i] != 0){
                sb.append(i).append(" ").append(arr[i]).append("\n");
            }
        }
        System.out.println(sb.toString());
    }
}

总结：

1、以前那种数组下边代替map的方式在这里优势不明显了、因为可以很随意设置

2、新的获取值得方式

StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
st.nextToken();        // 分隔符 
int n = (int) st.nval; // 强转

我组合的题解

import java.util.*;
import java.io.*;
public class Main {
    public static void main(String[] args) throws IOException {
        StreamTokenizer st = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        st.nextToken();      // 分隔符
        int n = (int) st.nval;   // 强转
        TreeMap<Integer, Integer> map = new TreeMap<>();

        for (int i = 0; i < n; i++) {
            st.nextToken();
            int key = (int) st.nval;
            st.nextToken();
            int value = (int) st.nval;
            if (map.containsKey(key)) {
                map.put(key, map.get(key) + value);
            } else {
                map.put(key, value);
            }
        }

        for (int e : map.keySet()) {
            System.out.println(e + " " + map.get(e));
        }
    }
}

总结：

1、 要去学习一下StreamTokenizer

2、Map的基础方法需要复习巩固一下