java两个大数字相加

最新推荐文章于 2021-06-20 10:03:55 发布

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最新推荐文章于 2021-06-20 10:03:55 发布

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文章标签： java

原文链接：https://my.oschina.net/itfanr/blog/195624

为什么80%的码农都做不了架构师？>>>

package com.duapp.itfanr;

import java.math.*;
import java.util.Arrays;

public class CharDemo {

	public static void main(String args[]) {
		String num1 = "1234";
		String num2 = "789";//此处没有考虑到负数情况
		System.out.print(plusBigNum(num1, num2));
	}

	static String plusBigNum(String num1, String num2) {

		int len1 = num1.length();
		int len2 = num2.length();
		// 格式化两个数，使之长度相同
		if (len1 > len2) {
			for (int i = 0; i < len1 - len2; i++) {
				num2 = "0" + num2;
			}
		} else if (len2 > len1) {
			for (int i = 0; i < len2 - len1; i++) {
				num1 = "0" + num1;
			}
		}

		int[] numArr1 = str2IntArr(num1);
		int[] numArr2 = str2IntArr(num2);
		int[] result = add(numArr1, numArr2);

		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < result.length; i++) {
			if (result[result.length-1] ==0 &&i==result.length-1){
				break ; 			
			}
			else sb.append(result[i]);
		}

		return sb.reverse().toString();
	}

	static int[] str2IntArr(String str) {

		StringBuffer sb = new StringBuffer(str);
		String rvsstr = sb.reverse().toString();
		int len = rvsstr.length();
		int[] out = new int[len];
		for (int i = 0; i < len; i++) {

			out[i] = Integer.parseInt(rvsstr.charAt(i) + "");

		}
		return out;
	}

	public static int[] add(int a[], int b[]) {
		int maxLen = a.length;
		int[] sum = new int[maxLen + 1];
		int d = 0; 
		for (int i = 0; i < maxLen; i++) {
			int tempSum = a[i] + b[i] + d;
			sum[i] = tempSum % 10;
			d = tempSum / 10; // 进位			
		}
		return sum;
	}

}

Integer.parseInt 用于将字符转为十进制数字 myString.charAt 用于String转字符数组参考： [1]. http://for-dream.iteye.com/blog/1570479 [2]. http://bbs.youkuaiyun.com/topics/240045624 [3]. http://hehaiztc.iteye.com/blog/1175538

转载于:https://my.oschina.net/itfanr/blog/195624