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| 1 | +package crackingTheCodingInterview.chap2; |
| 2 | + |
| 3 | +import me.premaseem.myLib.MySLLNode; |
| 4 | +import org.junit.Test; |
| 5 | + |
| 6 | +/** |
| 7 | + * ### Sum Lists: |
| 8 | + * You have two numbers represented by a linked list, where each node contains a single digit.The digits are stored in reverse order, such that the 1 's digit is at the head of the list. Write a function that adds the two numbers and returns the sum as a linked list. |
| 9 | + * EXAMPLE |
| 10 | + * Input:(7-> 1 -> 6) + (5 -> 9 -> 2).Thatis,617 + 295. Output:2 -> 1 -> 9.Thatis,912. |
| 11 | + * <p> |
| 12 | + * FOLLOW UP |
| 13 | + * Suppose the digits are stored in forward order. Repeat the above problem. EXAMPLE |
| 14 | + * lnput:(6 -> 1 -> 7) + (2 -> 9 -> 5).That is,617 + 295. Output:9 -> 1 -> 2.Thatis,912. |
| 15 | + */ |
| 16 | +public class SumLists { |
| 17 | + // Test Driven Development by Aseem Jain |
| 18 | + @Test |
| 19 | + public void test() { |
| 20 | + |
| 21 | + int[] n1 = new int[]{7, 1, 3}; |
| 22 | + int[] n2 = new int[]{6, 3, 4, 8, 2}; |
| 23 | + |
| 24 | + MySLLNode head1 = new MySLLNode(n1); |
| 25 | + MySLLNode head2 = new MySLLNode(n2); |
| 26 | + |
| 27 | + MySLLNode head3 = solution1(head1, head2); |
| 28 | + assert head3.toInt() == 64195; |
| 29 | + |
| 30 | + |
| 31 | + } |
| 32 | + |
| 33 | + // Basic solution |
| 34 | + private MySLLNode solution1(MySLLNode h1, MySLLNode h2) { |
| 35 | + // take pointer back if DLL else reverse it |
| 36 | + // start adding last digits and savce in new ll node; |
| 37 | + // take care of carry overs |
| 38 | + |
| 39 | + MySLLNode ans = null; |
| 40 | + MySLLNode newHead = null; |
| 41 | + |
| 42 | + h1 = h1.reverse(); |
| 43 | + h2 = h2.reverse(); |
| 44 | + |
| 45 | + |
| 46 | + int carry = 0; |
| 47 | + |
| 48 | + while (h1 != null || h2 != null || carry != 0) { |
| 49 | + int d = 0; |
| 50 | + |
| 51 | + if (h1 != null) { |
| 52 | + d += h1.data; |
| 53 | + h1 = h1.next; |
| 54 | + } |
| 55 | + |
| 56 | + if (h2 != null) { |
| 57 | + d += h2.data; |
| 58 | + h2 = h2.next; |
| 59 | + } |
| 60 | + |
| 61 | + if (carry != 0) { |
| 62 | + d += carry; |
| 63 | + } |
| 64 | + |
| 65 | + carry = d / 10; |
| 66 | + d = d % 10; |
| 67 | + MySLLNode nn = new MySLLNode(d); |
| 68 | + System.out.println(nn.data); |
| 69 | + nn.next = ans; |
| 70 | + ans = nn; |
| 71 | + newHead = nn; |
| 72 | + } |
| 73 | + |
| 74 | + return newHead; |
| 75 | + } |
| 76 | + |
| 77 | +} |
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