1002. A+B for Polynomials (25)

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

Input

Each input file contains one test case. Each case occupies 2 lines, and each line contains the information of a polynomial: K N1 a_N1 N2 a_N2 ... NK a_NK, where K is the number of nonzero terms in the polynomial, Ni and a_Ni (i=1, 2, ..., K) are the exponents and coefficients, respectively. It is given that 1 <= K <= 10，0 <= NK < ... < N2 < N1 <=1000.

Output

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

思路：因为题目给了指数的范围<1000,利用数组实现简易的Hash表。

PS：题目有一个不严谨的地方，判断系数和是否为0这里。只用简单的 coffi[i]!=0 是不对的，如果系数的绝对值<0.05,在保留一位小数的情况下就成了0,0是不应该被输出的。正确的判断形式应该是Math.abs(coffi[i])>=0.05，两种写法都可以通过测试用例。

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int K=in.nextInt();
        float[] coffi=new float[1001];
        for(int i=0;i<K;i++){
            coffi[in.nextInt()]+=in.nextFloat();
        }
        K=in.nextInt();
        for(int i=0;i<K;i++){
            coffi[in.nextInt()]+=in.nextFloat();
        }
        int count=0;
        StringBuilder sb=new StringBuilder();
        for(int i=coffi.length-1;i>=0;i--){
            if(coffi[i]!=0){  //May be Math.abs(coffi[i])>=0.05 is better
                count++;
                sb.append(String.format(" %d %.1f",i,coffi[i]));
            }
        }
        System.out.println(count+sb.toString());


    }
}