You are given a string s containing lowercase English letters, and a matrix shift , where shift[i] = [direction, amount] :

direction can be 0 (for left shift) or 1 (for right shift). amount is the amount by which string s is to be shifted. A left shift by 1 means remove the first character of s and append it to the end. Similarly, a right shift by 1 means remove the last character of s and add it to the beginning.

Return the final string after all operations.

Example 1:

Input: s = "abc", shift = [[0,1],[1,2]] Output: "cab" Explanation: [0,1] means shift to left by 1. "abc" -> "bca" [1,2] means shift to right by 2. "bca" -> "cab"

Example 2:

Input: s = "abcdefg", shift = [[1,1],[1,1],[0,2],[1,3]] Output: "efgabcd" Explanation: [1,1] means shift to right by 1. "abcdefg" -> "gabcdef" [1,1] means shift to right by 1. "gabcdef" -> "fgabcde" [0,2] means shift to left by 2. "fgabcde" -> "abcdefg" [1,3] means shift to right by 3. "abcdefg" -> "efgabcd"

Constraints:

1 <= s.length <= 100 s only contains lower case English letters. 1 <= shift.length <= 100 shift[i].length == 2 0 <= shift[i][0] <= 1 0 <= shift[i][1] <= 100

Solution – Easy to understand

C# Program

public class Solution { public string StringShift(string s, int[][] shift) { int sum = 0; foreach(int[] arr in shift) { if(arr[0] == 0){ sum = sum - arr[1]; } else{ sum = sum + arr[1]; } } int len = s.Length; //To order length below string length if(sum > len || -sum > len){ sum = sum % len; } if(sum > 0){ //Performing right reversal int d = len - sum; string result = s.Substring(d) + s.Substring(0,d); return result; } else if(sum < 0){ //Performing left reversal sum = Math.Abs(sum); string result = s.Substring(sum) + s.Substring(0,sum); return result; } return s; } }

Code Walk Through

Time Complexity: O(n)

Space Complexity: O(1)