import java.util.Scanner; public class Main {     public static void main(String[] args) {         Scanner input = new Scanner(System.in);         String num1 = input.nextLine();         String num2 = input.nextLine();         String sum = add(num1, num2);         System.out.println(sum);     }     /*      * 1234567890123456789012345678901234567890.      * 1234567890123456789012345678901234567890      * 1000000000100000000010000000001000000000.      * 1000000000100000000010000000001000000000      */     /*      * 2234567890223456789022345678902234567890.      * 223456789022345678902234567890223456789      */     private static String[] split(String str) {         for (int i = 0; i < str.length(); i++) {             if (str.charAt(i) == '.') {                 return new String[] { str.substring(0, i), str.substring(i + 1) };             }         }         return new String[] { str, "" };     }     private static String add(String num1, String num2) {         /*String[] number1 = num1.split("\\.");         String[] number2 = num2.split("\\.");*/         String[] number1 = split(num1);         String[] number2 = split(num2);         String nums1 = number1[0];         String nums2 = number2[0];         String dot1 = number1[1];         String dot2 = number2[1];         int dlength1 = dot1.length();         int dlength2 = dot2.length();         int min;         int[] dnums = new int[dlength1 > dlength2 ? dlength1 : dlength2];         if (dlength1 > dlength2) {             min = dlength2;             for (int i = min; i < dlength1; i++) {                 dnums[i] = dot1.charAt(i) - '0';             }         } else {             min = dlength1;             for (int i = min; i < dlength2; i++) {                 dnums[i] = dot2.charAt(i) - '0';             }         }         min--;         int top = 0;         while (min >= 0) {             int sum = (dot1.charAt(min) + dot2.charAt(min) + dnums[min] - 2 * '0');             if (sum >= 10) {                 dnums[min] = sum % 10;                 if (min != 0) {                     dnums[--min] = sum / 10;                 } else {                     top = sum / 10;                 }             } else {                 dnums[min--] = sum;             }         }         int[] num = new int[(nums1.length() > nums2.length() ? nums1.length() : nums2.length()) + 1];         int i = nums1.length() - 1;         int j = nums2.length() - 1;         int k = num.length - 1;         num[k] = top;         while (i >= 0 && j >= 0) {             int sum = (nums1.charAt(i) + nums2.charAt(j) + num[k] - 2 * '0');             if (sum >= 10) {                 num[k] = sum % 10;                 num[--k] = sum / 10;             } else {                 num[k--] = sum;             }             i--;             j--;         }         if (i < 0 || j >= 0) {             while (j >= 0) {                 int sum = (nums2.charAt(j) + num[k]) - '0';                 if (sum >= 10) {                     num[k] = sum % 10;                     num[--k] = sum / 10;                 } else {                     num[k--] = sum;                 }                 j--;             }         } else if (i >= 0 || j < 0) {             while (i >= 0) {                 int sum = (nums1.charAt(i) + num[k]) - '0';                 if (sum >= 10) {                     num[k] = sum % 10;                     num[--k] = sum / 10;                 } else {                     num[k--] = sum;                 }                 i--;             }         }         StringBuilder sb = new StringBuilder();         StringBuilder sb1 = new StringBuilder();         boolean sign = false, sign1 = false;         for (int s : num) {             if (s != 0)                 sign = true;             if (sign) {                 sb.append(s);             }         }         for (int h = dnums.length - 1; h >= 0; h--) {             if (dnums[h] != 0)                 sign1 = true;             if (sign1) {                 sb1.append(dnums[h]);                 if (h == 0)                     sb1.append(".");             }         }         sb.append(sb1.reverse());         return sb.toString();     } } 思路是不难，代码量太大了吧！！！