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Calculate nCr in counting all possible paths problem

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问题 I have a doubt in how did the author reach the intuition behind the formula to calculate the (m + n -2)C n-1 in this problem - https://www.geeksforgeeks.org/count-possible-paths-top-left-bottom-right-nxm-matrix/ Please scroll down to solution by using combinatorics. Particularly talking, I don't understand how the below code was developed for what is basically a nCr for (int i = n; i < (m + n - 1); i++) { path *= i; path /= (i - n + 1); } I mean, if I put values into it, I get it. But, if you

Calculate nCr in counting all possible paths problem

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Generating nCr combinations of given set in java [closed]

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问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I want java implementation of generating nCr combinations of given set. e.g if set is {"java","php",".net","python"} program should return all possible nCr sets of given set. 回答1: Adapting Gosper's hack, this

Regex Replacing : to “:” etc

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问题 I've got a bunch of strings like: "Hello, here's a test colon:. Here's a test semi-colon;" I would like to replace that with "Hello, here's a test colon:. Here's a test semi-colon;" And so on for all printable ASCII values. At present I'm using boost::regex_search to match &#(\d+); , building up a string as I process each match in turn (including appending the substring containing no matches since the last match I found). Can anyone think of a better way of doing it? I'm open to non-regex

Regex Replacing : to “:” etc

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I've got a bunch of strings like: "Hello, here's a test colon:. Here's a test semi-colon;" I would like to replace that with "Hello, here's a test colon:. Here's a test semi-colon;" And so on for all printable ASCII values . At present I'm using boost::regex_search to match &#(\d+); , building up a string as I process each match in turn (including appending the substring containing no matches since the last match I found). Can anyone think of a better way of doing it? I'm open to non-regex methods, but regex seemed a reasonably sensible approach in this case. Thanks, Dom The big advantage of