Task: Range consolidation


C++: #include <algorithm>
#include <iostream>
#include <utility>
#include <vector>



template <typename iterator>
void normalize_ranges(iterator begin, iterator end) {
    for (iterator i = begin; i != end; ++i) {
        if (i->second < i->first)
            std::swap(i->first, i->second);
    }
    std::sort(begin, end);
}



template <typename iterator>
iterator merge_ranges(iterator begin, iterator end) {
    iterator out = begin;
    for (iterator i = begin; i != end; ) {
        iterator j = i;
        while (++j != end && j->first <= i->second)
            i->second = std::max(i->second, j->second);
        *out++ = *i;
        i = j;
    }
    return out;
}

template <typename iterator>
iterator consolidate_ranges(iterator begin, iterator end) {
    normalize_ranges(begin, end);
    return merge_ranges(begin, end);
}

template <typename pair>
void print_range(std::ostream& out, const pair& range) {
    out << '[' << range.first << ", " << range.second << ']';
}

template <typename iterator>
void print_ranges(std::ostream& out, iterator begin, iterator end) {
    if (begin != end) {
        print_range(out, *begin++);
        for (; begin != end; ++begin) {
            out << ", ";
            print_range(out, *begin);
        }
    }
}

int main() {
    std::vector<std::pair<double, double>> test_cases[] = {
        { {1.1, 2.2} },
        { {6.1, 7.2}, {7.2, 8.3} },
        { {4, 3}, {2, 1} },
        { {4, 3}, {2, 1}, {-1, -2}, {3.9, 10} },
        { {1, 3}, {-6, -1}, {-4, -5}, {8, 2}, {-6, -6} }
    };
    for (auto&& ranges : test_cases) {
        print_ranges(std::cout, std::begin(ranges), std::end(ranges));
        std::cout << " -> ";
        auto i = consolidate_ranges(std::begin(ranges), std::end(ranges));
        print_ranges(std::cout, std::begin(ranges), i);
        std::cout << '\n';
    }
    return 0;
}



Go: package main

import (
    "fmt"
    "math"
    "sort"
)

type Range struct{ Lower, Upper float64 }

func (r Range) Norm() Range {
    if r.Lower > r.Upper {
        return Range{r.Upper, r.Lower}
    }
    return r
}

func (r Range) String() string {
    return fmt.Sprintf("[%g, %g]", r.Lower, r.Upper)
}

func (r1 Range) Union(r2 Range) []Range {
    if r1.Upper < r2.Lower {
        return []Range{r1, r2}
    }
    r := Range{r1.Lower, math.Max(r1.Upper, r2.Upper)}
    return []Range{r}
}

func consolidate(rs []Range) []Range {
    for i := range rs {
        rs[i] = rs[i].Norm()
    }
    le := len(rs)
    if le < 2 {
        return rs
    }
    sort.Slice(rs, func(i, j int) bool {
        return rs[i].Lower < rs[j].Lower
    })
    if le == 2 {
        return rs[0].Union(rs[1])
    }
    for i := 0; i < le-1; i++ {
        for j := i + 1; j < le; j++ {
            ru := rs[i].Union(rs[j])
            if len(ru) == 1 {
                rs[i] = ru[0]
                copy(rs[j:], rs[j+1:])
                rs = rs[:le-1]
                le--
                i--
                break
            }
        }
    }
    return rs
}

func main() {
    rss := [][]Range{
        {{1.1, 2.2}},
        {{6.1, 7.2}, {7.2, 8.3}},
        {{4, 3}, {2, 1}},
        {{4, 3}, {2, 1}, {-1, -2}, {3.9, 10}},
        {{1, 3}, {-6, -1}, {-4, -5}, {8, 2}, {-6, -6}},
    }
    for _, rs := range rss {
        s := fmt.Sprintf("%v", rs)
        fmt.Printf("%40s => ", s[1:len(s)-1])
        rs2 := consolidate(rs)
        s = fmt.Sprintf("%v", rs2)
        fmt.Println(s[1 : len(s)-1])
    }
}