Automatic Editing
InterviewTime limit1sMemory limit128 MB
Apply a fixed list of find-and-replace rules in order, repeatedly replacing the first occurrence of each find string until it no longer appears, and print the final text.
- Level
Medium4 of 10
- Topics
- String, Simulation, Implementation, String matching
- Solved
- No attempts yet
Problem
Text-processing tools such as awk and sed let you automatically perform a sequence of editing operations driven by a script. In this problem we consider the specific case of performing a series of string replacements, within a single line of text, based on a fixed set of rules. Each rule specifies the string to find and the string to replace it with, as shown below.
To edit a given line of text, start with the first rule. Replace the first occurrence of the find string within the text by the replace-by string, then try to perform the same replacement again on the new text. Continue until the find string no longer occurs in the text, then move on to the next rule. Continue until every rule has been considered. Note that (1) when searching for a find string you always start searching at the beginning of the text, (2) once you have finished with a rule (because the find string no longer occurs) you never use that rule again, and (3) case is significant.
For example, suppose we start with the line
banana boat
and apply these rules. The sequence of transformations is shown below, where occurrences of a find string are italicized and replacements are bold. Rule 1 was used twice, then rule 2 once, then rule 3 zero times, and then rule 4 once.
Input
The input contains one or more test cases, followed by a line containing only 0 (zero) that signals the end of the input. Each test case begins with a line containing the number of rules, which is between 1 and 10. Each rule is given by a pair of lines: the first line is the find string and the second line is the replace-by string. After all the rules comes a line containing the text to edit.
Output
For each test case, output a line containing the final edited text.
Notes
Both the find and replace-by strings are at most 80 characters long. Find strings contain at least one character, but replace-by strings may be empty (represented in the input by an empty line). During the editing process the text may grow to as many as 255 characters, but the final output text is fewer than 80 characters long.
The first sample test case corresponds to the example shown above.