{ "data": { "question": { "questionId": "2562", "questionFrontendId": "2466", "boundTopicId": null, "title": "Count Ways To Build Good Strings", "titleSlug": "count-ways-to-build-good-strings", "content": "
Given the integers zero
, one
, low
, and high
, we can construct a string by starting with an empty string, and then at each step perform either of the following:
'0'
zero
times.'1'
one
times.This can be performed any number of times.
\n\nA good string is a string constructed by the above process having a length between low
and high
(inclusive).
Return the number of different good strings that can be constructed satisfying these properties. Since the answer can be large, return it modulo 109 + 7
.
\n
Example 1:
\n\n\nInput: low = 3, high = 3, zero = 1, one = 1\nOutput: 8\nExplanation: \nOne possible valid good string is "011". \nIt can be constructed as follows: "" -> "0" -> "01" -> "011". \nAll binary strings from "000" to "111" are good strings in this example.\n\n\n
Example 2:
\n\n\nInput: low = 2, high = 3, zero = 1, one = 2\nOutput: 5\nExplanation: The good strings are "00", "11", "000", "110", and "011".\n\n\n
\n
Constraints:
\n\n1 <= low <= high <= 105
1 <= zero, one <= low
Compiled with clang 11
using the latest C++ 20 standard.
Your code is compiled with level two optimization (-O2
). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
\"], \"java\": [\"Java\", \"OpenJDK 17
. Java 8 features such as lambda expressions and stream API can be used.
Most standard library headers are already included automatically for your convenience.
\\r\\nIncludes Pair
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Python 2.7.12
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\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
\\r\\n\\r\\nNote that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.
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\\r\\n\\r\\nFor hash table operations, you may use uthash. \\\"uthash.h\\\" is included by default. Below are some examples:
\\r\\n\\r\\n1. Adding an item to a hash.\\r\\n
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Node.js 16.13.2
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Your code is run with --harmony
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lodash.js library is included by default.
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Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms
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Go 1.21
Support https://godoc.org/github.com/emirpasic/gods@v1.18.1 library.
\"], \"python3\": [\"Python3\", \"Python 3.10
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Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.
\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
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Kotlin 1.9.0
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Rust 1.58.1
Supports rand v0.6\\u00a0from crates.io
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.
With bcmath module
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Dart 2.17.3
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