## Sunday, September 4, 2016

### Subtract Two Numbers represented as Linked Lists - GeeksforGeeks

Subtract Two Numbers represented as Linked Lists - GeeksforGeeks
Given two linked lists that represent two large positive numbers. Subtract the smaller number from larger one and return the difference as a linked list. Note that the input lists may be in any order, but we always need to subtract smaller from larger one.
It may be assumed that there are no extra leading zeros in input lists.

```Input  : l1 = 1 -> 0 -> 0 -> NULL,  l2 = 1 -> NULL
Output : 0->9->9->NULL
```
1) Calculate sizes of given two linked lists.
2) If sizes not are same, then append zeros in smaller linked list.
3) If size are same, then follow below steps:
….a) Find the smaller valued linked list.
….b) One by one subtract nodes of smaller sized linked list from larger size. Keep track of borrow while subtracting.
`/* A utility function to get length of linked list */`
`int` `getLength(Node *Node)`
`{`
`    ``int` `size = 0;`
`    ``while` `(Node != NULL)`
`    ``{`
`        ``Node = Node->next;`
`        ``size++;`
`    ``}`
`    ``return` `size;`
`}`

`/* A Utility that padds zeros in front of the`
`   ``Node, with the given diff */`
`Node* paddZeros(Node* sNode, ``int` `diff)`
`{`
`    ``if` `(sNode == NULL)`
`        ``return` `NULL;`

`    ``Node* zHead = newNode(0);`
`    ``diff--;`
`    ``Node* temp = zHead;`
`    ``while` `(diff--)`
`    ``{`
`        ``temp->next = newNode(0);`
`        ``temp = temp->next;`
`    ``}`
`    ``temp->next = sNode;`
`    ``return` `zHead;`
`}`

`/* Subtract LinkedList Helper is a recursive function,`
`   ``move till the last Node,  and subtract the digits and`
`   ``create the Node and return the Node. If d1 < d2, we`
`   ``borrow the number from previous digit. */`
`Node* subtractLinkedListHelper(Node* l1, Node* l2, ``bool``& borrow)`
`{`
`    ``if` `(l1 == NULL && l2 == NULL && borrow == 0)`
`        ``return` `NULL;`

`    ``Node* previous = subtractLinkedListHelper(l1 ? l1->next : NULL,`
`                                    ``l2 ? l2->next : NULL, borrow);`

`    ``int` `d1 = l1->data;`
`    ``int` `d2 = l2->data;`
`    ``int` `sub = 0;`

`    ``/* if you have given the value value to next digit then`
`       ``reduce the d1 by 1 */`
`    ``if` `(borrow)`
`    ``{`
`        ``d1--;`
`        ``borrow = ``false``;`
`    ``}`

`    ``/* If d1 < d2 , then borrow the number from previous digit.`
`       ``Add 10 to d1 and set borrow = true; */`
`    ``if` `(d1 < d2)`
`    ``{`
`        ``borrow = ``true``;`
`        ``d1 = d1 + 10;`
`    ``}`

`    ``/* subtract the digits */`
`    ``sub = d1 - d2;`

`    ``/* Create a Node with sub value */`
`    ``Node* current = newNode(sub);`

`    ``/* Set the Next pointer as Previous */`
`    ``current->next = previous;`

`    ``return` `current;`
`}`

`/* This API subtracts two linked lists and returns the`
`   ``linked list which shall  have the subtracted result. */`
`Node* subtractLinkedList(Node* l1, Node* l2)`
`{`
`    ``// Base Case.`
`    ``if` `(l1 == NULL &&  l2 == NULL)`
`        ``return` `NULL;`

`    ``// In either of the case, get the lengths of both`
`    ``// Linked list.`
`    ``int` `len1 = getLength(l1);`
`    ``int` `len2 = getLength(l2);`

`    ``Node *lNode = NULL, *sNode = NULL;`

`    ``Node* temp1 = l1;`
`    ``Node* temp2 = l2;`

`    ``// If lengths differ, calculate the smaller Node`
`    ``// and padd zeros for smaller Node and ensure both`
`    ``// larger Node and smaller Node has equal length.`
`    ``if` `(len1 != len2)`
`    ``{`
`        ``lNode = len1 > len2 ? l1 : l2;`
`        ``sNode = len1 > len2 ? l2 : l1;`
`        ``sNode = paddZeros(sNode, ``abs``(len1 - len2));`
`    ``}`

`    ``else`
`    ``{`
`        ``// If both list lengths are equal, then calculate`
`        ``// the larger and smaller list. If 5-6-7 & 5-6-8`
`        ``// are linked list, then walk through linked list`
`        ``// at last Node as 7 < 8, larger Node is 5-6-8`
`        ``// and smaller Node is 5-6-7.`
`        ``while` `(l1 && l2)`
`        ``{`
`            ``if` `(l1->data != l2->data)`
`            ``{`
`                ``lNode = l1->data > l2->data ? temp1 : temp2;`
`                ``sNode = l1->data > l2->data ? temp2 : temp1;`
`            ``}`
`            ``l1 = l1->next;`
`            ``l2 = l2->next;`
`        ``}`
`    ``}`

`    ``// After calculating larger and smaller Node, call`
`    ``// subtractLinkedListHelper which returns the subtracted`
`    ``// linked list.`
`    ``bool` `borrow = ``false``;`
`    ``return` `subtractLinkedListHelper(lNode, sNode, borrow);`
`}`
Read full article from Subtract Two Numbers represented as Linked Lists - GeeksforGeeks

## Labels

GeeksforGeeks (1107) LeetCode (993) Algorithm (795) Review (766) to-do (633) LeetCode - Review (514) Classic Algorithm (324) Dynamic Programming (293) Classic Interview (288) Google Interview (242) Tree (145) POJ (139) Difficult Algorithm (132) LeetCode - Phone (127) EPI (125) Different Solutions (120) Bit Algorithms (118) Lintcode (113) Smart Algorithm (109) Math (107) HackerRank (89) Binary Tree (82) Binary Search (81) Graph Algorithm (74) Greedy Algorithm (72) DFS (67) Interview Corner (61) Stack (60) List (58) BFS (54) Codility (54) ComProGuide (52) USACO (46) Trie (45) ACM-ICPC (41) Interval (41) Data Structure (40) Knapsack (40) Jobdu (39) LeetCode Hard (39) Matrix (38) String Algorithm (38) Backtracking (36) Codeforces (36) Must Known (36) Sort (35) Union-Find (34) Array (33) prismoskills (33) Segment Tree (32) Sliding Window (32) HDU (31) Google Code Jam (30) Permutation (30) Puzzles (30) Array O(N) (29) Company-Airbnb (29) Company-Zenefits (28) Palindrome (28) to-do-must (28) Priority Queue (27) Random (27) Graph (26) GeeksQuiz (25) Logic Thinking (25) Pre-Sort (25) hihocoder (25) Queue (24) Company-Facebook (23) High Frequency (23) TopCoder (23) Algorithm Game (22) Bisection Method (22) Hash (22) DFS + Review (21) Brain Teaser (20) CareerCup (20) Merge Sort (20) O(N) (20) Follow Up (19) Time Complexity (19) Two Pointers (19) UVA (19) Ordered Stack (18) Probabilities (18) Company-Uber (17) Game Theory (17) Topological Sort (17) Codercareer (16) Heap (16) Shortest Path (16) String Search (16) Tree Traversal (16) itint5 (16) Difficult (15) Iterator (15) BST (14) Number (14) Number Theory (14) Amazon Interview (13) Basic Algorithm (13) Codechef (13) Euclidean GCD (13) KMP (13) Majority (13) mitbbs (13) Combination (12) Modify Tree (12) Reconstruct Tree (12) Reverse Thinking (12) 尺取法 (12) AOJ (11) DFS+Backtracking (11) Graph DFS (11) LCA (11) LeetCode - DFS (11) Miscs (11) Princeton (11) Proof (11) Tree DP (11) X Sum (11) 挑战程序设计竞赛 (11) Bisection (10) Bucket Sort (10) Coin Change (10) DFS+Cache (10) HackerRank Easy (10) O(1) Space (10) Rolling Hash (10) SPOJ (10) Theory (10) Tutorialhorizon (10) Mathblog (9) Max-Min Flow (9) Prefix Sum (9) Quick Sort (9) Simulation (9) Stock (9) TreeMap (9) Use XOR (9) Book Notes (8) Bottom-Up (8) DFS+BFS (8) Linked List (8) Prime (8) Suffix Tree (8) Tech-Queries (8) 穷竭搜索 (8) Expression (7) Game Nim (7) Graph BFS (7) Hackerearth (7) Inversion (7) Quick Select (7) Radix Sort (7) n00tc0d3r (7) 蓝桥杯 (7) DFS+DP (6) DP - Tree (6) Dijkstra (6) Dutch Flag (6) How To (6) Manacher (6) One Pass (6) Pruning (6) Rabin-Karp (6) Sampling (6) Schedule (6) Stream (6) Suffix Array (6) Threaded (6) TreeSet (6) Xpost (6) reddit (6) AI (5) Big Data (5) Brute Force (5) Code Kata (5) Coding (5) Convex Hull (5) Crazyforcode (5) Cycle (5) Find Rule (5) Graph Cycle (5) Immutability (5) Java (5) Maze (5) Pre-Sum (5) Quadtrees (5) Quora (5) Subarray Sum (5) Sudoku (5) Sweep Line (5) Word Search (5) jiuzhang (5) 单调栈 (5) 树形DP (5) 1point3acres (4) Abbreviation (4) Anagram (4) Anagrams (4) Chess Game (4) Distributed (4) Flood fill (4) Histogram (4) MST (4) MinMax (4) N Queens (4) Probability (4) Programcreek (4) Subset Sum (4) Subsets (4) Symbol Table (4) Triangle (4) Water Jug (4) algnotes (4) fgdsb (4) to-do-2 (4) 最大化最小值 (4) A Star (3) B Tree (3) Coins (3) Dedup (3) Dequeue (3) Dropbox (3) Easy (3) Github (3) GoLang (3) Joseph (3) Jump Game (3) K (3) LogN (3) Minesweeper (3) NP Hard (3) O(N) Hard (3) Rectangle (3) Scala (3) SegmentFault (3) Shuffle (3) Subtree (3) Trie + DFS (3) Word Ladder (3) bookkeeping (3) codebytes (3) Array Merge (2) BOJ (2) Bellman Ford (2) Bit Counting (2) Bit Mask (2) Bloom Filter (2) Clock (2) Codesays (2) DP - DFS (2) DP-3D Table (2) DP-Classical (2) DP-i-k-j (2) DP-树形 (2) Factor (2) GoHired (2) Graham Scan (2) Huffman Tree (2) Invariant (2) Islands (2) Lucene-Solr (2) Matrix Power (2) Median (2) Parentheses (2) Parser (2) Peak (2) Programming (2) Robot (2) Rosettacode (2) Search (2) SimHash (2) Skyline (2) Summary (2) TV (2) Tile (2) Tree Sum (2) Word Break (2) Word Graph (2) Word Trie (2) 剑指Offer (2) 数位DP (2) 1-X (1) 51Nod (1) Akka (1) BACK (1) BK-Tree (1) BZOJ (1) Basic (1) Bayes (1) Big Integer (1) Big Number (1) Binary (1) Bipartite (1) BitMap (1) BitMap index (1) BitSet (1) BuildIt (1) C/C++ (1) CC Interview (1) Cache (1) Chinese (1) Cloest (1) Clone (1) Code Quality (1) Company-Epic (1) Company-Yelp (1) Concurrency (1) Custom Sort (1) DFS-Matrix (1) DP-Difficult (1) DP-Graph (1) DP-MaxMin (1) Database (1) Diagonal (1) Domino (1) Dr Dobb's (1) Duplicate (1) FST (1) Fraction (1) Funny (1) Game (1) Generation (1) GeoHash (1) Google APAC (1) Gray Code (1) HOJ (1) Hanoi (1) How Hash (1) How to Test (1) Improve It (1) In Place (1) Interview (1) Isomorphic (1) JDK8 (1) Knight (1) Kruskal (1) Kth Element (1) Linkedin (1) Local MinMax (1) Matrix BFS (1) Matrix Graph (1) Matrix+DP (1) MinHash (1) MinMax Heap (1) Monto Carlo (1) Multiple DFS (1) Next Element (1) PAT (1) Parenthesis (1) Partition (1) Path Finding (1) Persistent (1) Power Set (1) PreProcess (1) Python (1) RSA (1) Ranking (1) Rddles (1) ReHash (1) Realtime (1) Region (1) Resources (1) Robin (1) Selection (1) Similarity (1) Square (1) String DP (1) SubMatrix (1) Subsequence (1) TSP (1) Test (1) Test Cases (1) Thread (1) TimSort (1) Top-Down (1) Tournament (1) Tree Rotate (1) Trie vs Hash (1) Triplet (1) Two Stacks (1) UyHiP (1) Valid Tree (1) Vector (1) Wiggle Sort (1) Wikipedia (1) ZOJ (1) ZigZag (1) codevs (1) cos126 (1) javabeat (1) jum (1) sqrt(N) (1) 两次dijkstra (1) 九度 (1) 二进制枚举 (1) 夹逼法 (1) 归一化 (1) 折半枚举 (1) 枚举 (1) 状态压缩DP (1) 男人八题 (1) 英雄会 (1) 逆向思维 (1)