Range Extraction
A format for expressing an ordered list of integers is to use a comma separated list of either
individual integers
or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. The range includes all integers in the interval including both endpoints. It is not considered a range unless it spans at least 3 numbers. For example ("12, 13, 15-17")
Complete the solution so that it takes a list of integers in increasing order and returns a correctly formatted string in the range format.
Example:
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]);
// returns "-6,-3-1,3-5,7-11,14,15,17-20"
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
solution([-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
Solution.rangeExtraction(new int[] {-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20})
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
RangeExtraction.Extract(new[] {-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20});
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
range_extraction({-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20});
// returns "-6,-3-1,3-5,7-11,14,15,17-20"
range_extraction((const []){-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20}, 20);
/* returns "-6,-3-1,3-5,7-11,14,15,17-20" */
nums: dd -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20
mov rdi, nums
mov rsi, 20
call range_extraction
; RAX <- `-6,-3-1,3-5,7-11,14,15,17-20\0`
rangeextraction([-6 -3 -2 -1 0 1 3 4 5 7 8 9 10 11 14 15 17 18 19 20])
# returns "-6,-3-1,3-5,7-11,14,15,17-20"
solution(List(-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20))
// "-6,-3-1,3-5,7-11,14,15,17-20"
(solution '(-6 -3 -2 -1 0 1 3 4 5 7 8 9 10 11 14 15 17 18 19 20))
; returns "-6,-3-1,3-5,7-11,14,15,17-20"
Courtesy of rosettacode.org
Solutions
🧠 C++
#include <string>
#include <vector>
using std::to_string;
std::string range_extraction(std::vector<int> args)
{
std::string res = to_string(args[0]);
bool is_range = false;
for (int i = 1, prev = args[0], range_len = 0;
i < args.size(); prev = args[i++])
{
int fi = i == args.size()-1;
if (args[i] == prev+1)
{
is_range = true;
range_len++;
}
if (fi) //special logic for the last element
{
if (range_len > 1 && args[i] == prev+1)
res+='-'+ to_string(args[i]);
else if (range_len > 1) // but last element is not part of the seq
res+='-'+ to_string(args[i-1])+','+to_string(args[i]);
else if (range_len == 1 && args[i] != prev+1)
res+=',' + to_string(args[i-1]) +','+to_string(args[i]);
else
res+=',' + to_string(args[i]);
break;
}
else if(args[i] != prev+1) // non sequence logic
{
if(range_len) //we got here every time when sequence ends
{
if (range_len > 1)
res+='-'+ to_string(args[i-1]);
else if (range_len == 1)
res+=',' + to_string(args[i-1]);
range_len = 0;
is_range = false;
}
res+=',' + to_string(args[i]);
}
}
return res;
}
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