1002 A+B for Polynomials (25 point(s)) 多项式加法

￡神魔★判官ぃ 2021-09-29 03:04 193阅读 0赞

# 1002 A+B for Polynomials (25 point(s)) #

This time, you are supposed to find A+B where A and B are two polynomials.

### Input Specification: ###

Each input file contains one test case. Each case occupies 2 lines, and each line contains the information of a polynomial:

K N1 aN1 N2 aN2 ... NK aNK

where K is the number of nonzero terms in the polynomial, Ni and aNi (i=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤10，0≤NK<⋯<N2<N1≤1000.

### Output Specification: ###

For each test case you should output the sum of A and B in one line, with the same format as the input. Notice that there must be NO extra space at the end of each line. Please be accurate to 1 decimal place.

### Sample Input: ###

2 1 2.4 0 3.2
    2 2 1.5 1 0.5

### Sample Output: ###

3 2 1.5 1 2.9 0 3.2

题目的要求就是完成两个多项式的加法。输入和输出的格式均是： 多项式的项数  指数1  系数1...指数n 系数n

package test;
    
    import java.util.*;
    
    /**
     * @Description:输入两个多项式的项数 系数,指数，求和
     **/
    /*
     * 要点：1.格式问题：系数要精确到小数点后一位，输出结果的最后不能有空格
     *       2.要注意可能存在指数相同的两项相加后系数为0，这种情况要去掉该项
     *       3.选择TreeMap的原因：首先题目中说每一个多项式的指数是唯一的，因此可以用键值对的形式
     *       其次TreeMap是按照键的大小按升序排序的，让我们的输出更加方便
     */
    public class sumPolynomials {
        public static void main(String...args){
            int number1 = 0;
            Map<Integer,Double> map1 = new TreeMap<>();
            //TreeMap默认是按照键的大小升序排列，这里用Lambda表达式让结果降序排列
            Map<Integer,Double> map2 = new TreeMap<>((e1,e2)->{
                return e2-e1;
            });
    
            //输入初始化，按键值对的方式表示两个多项式
            Scanner input = new Scanner(System.in);
            number1 = input.nextInt();
            while(number1 != 0){
                int a = input.nextInt();
                double b = input.nextDouble();
                map1.put(a,b);
                number1--;
            }
            number1 = input.nextInt();
            while(number1 != 0){
                int a = input.nextInt();
                double b = input.nextDouble();
                map2.put(a,b);
                number1--;
            }
    
    
            Set<Integer> set = map1.keySet();
            for(Integer keys : set){
                if(map2.containsKey(keys)){
                    if(map2.get(keys)+map1.get(keys)==0){
                        map2.remove(keys);
                    }
                    else {
                        map2.replace(keys,map2.get(keys)+map1.get(keys));
                    }
                }
                else
                    map2.put(keys,map1.get(keys));
            }
    
            Set<Integer> set1 = map2.keySet();
            System.out.print(map2.size());
            for(Integer keys: set1){
                System.out.printf(" %d %.1f",keys,map2.get(keys));
            }
        }
    
    
    }