interviews/training->training

puzzles/training/find_gaps.cpp

@@ -0,0 +1,79 @@
+/*
+VIM: let b:lcppflags="-std=c++14 -O2 -pthread -I."
+VIM: let b:wcppflags="/O2 /EHsc /DWIN32"
+*/
+#include "stdafx.h"
+#include <iostream>
+#include <exception>
+#include <chrono>
+#include <vector>
+#include <algorithm>
+
+/*
+google-interview-questions
+
+You are given a sorted list of distinct integers from 0 to 99, for 
+instance [0, 1, 2, 50, 52, 75]. Your task is to produce a string 
+that describes numbers missing from the list; in this case 
+"3-49,51,53-74,76-99".
+
+Examples:
+
+[] <20>0-99<39>
+[0] <20>1-99<39>
+[3, 5] <20>0-2,4,6-99<39>
+*/
+
+inline 
+void print_range_if_not_empty(int rb, int re)
+{
+	if (re-rb > 2) {
+		std::cout << ',' << rb + 1 << '-' << re - 1;
+	}
+	else if (re-rb > 1) {
+		std::cout << ',' << rb + 1;
+	}
+}
+
+void print_gaps(std::vector<int> v)
+{
+	int v_prev = -1;
+	for (int i = 0; i < v.size(); v_prev = v[i++]) {
+		print_range_if_not_empty(v_prev, v[i]);
+	}
+	print_range_if_not_empty(v_prev, 100);
+	std::cout << std::endl;
+}
+
+int main()
+{
+	try {
+		auto begin = std::chrono::high_resolution_clock::now();
+
+
+		//......
+		print_gaps({ 0, 1, 2, 50, 52, 75 });
+		print_gaps({ 2, 4, 5, 7, 90 });
+		print_gaps({ 0, 4, 5, 7, 99 });
+
+
+
+
+		auto end = std::chrono::high_resolution_clock::now();
+		std::chrono::duration<double> seconds = end - begin;
+		std::cout << "Time: " << seconds.count() << std::endl;
+		return 0;
+	}
+	catch (const std::exception& e)
+	{
+		std::cerr << std::endl
+			<< "std::exception(\"" << e.what() << "\")." << std::endl;
+		return 2;
+	}
+	catch (...)
+	{
+		std::cerr << std::endl
+			<< "unknown exception." << std::endl;
+		return 1;
+	}
+}