This problem involves performing left and right shifts on a string based on a given shift matrix. The most efficient approach avoids repeatedly shifting the string for each operation in the matrix. Instead, it calculates the net shift and applies it once.
Algorithm:
Calculate Net Shift: Iterate through the shift
matrix. For each operation:
direction
is 0 (left shift), subtract the amount
from a running total x
.direction
is 1 (right shift), add the amount
to x
.Handle Modular Arithmetic: The net shift x
might be greater than the string length or negative. We use the modulo operator (%
) to wrap around. The expression (x % n + n) % n
ensures that x
is always a positive number within the range [0, n) where n is the string length. This correctly handles both positive and negative shifts beyond the string length.
Apply the Shift: After obtaining the effective shift x
, we can efficiently apply the shift by extracting substrings:
s[-x:]
takes the last x
characters (right shift).s[:-x]
takes the characters from the beginning to the index -x
(all but the last x
characters). These two substrings are concatenated to get the result.Time Complexity Analysis:
shift
matrix.s
.Space Complexity Analysis:
The solutions provided earlier demonstrate the algorithm in Python, Java, C++, Go, and TypeScript. Each solution follows the same algorithm, differing only in syntax. The core steps—calculating the net shift, handling modular arithmetic, and applying the shift using substring manipulation—remain consistent across all languages. Refer to the code examples in the previous response for detailed implementation.