#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdint>
#include <cstring>
#include <cassert>

static const char *argv0;

void usage() {
	std::cerr << "Usage: " << argv0 << " [<lowbound> <highbound>] [<nbins>]" << std::endl
	          << "Prints a simple histogram of stdin data in your terminal, using" << std::endl
	          << "either the given lower and upper bounds, or the minimum and" << std::endl
	          << "maximum extracted from the data." << std::endl
	          << "The number of bins can also be passed." << std::endl
	          << "Data on stdin is assumed to be a list of floating-point values." << std::endl;
}

double parsefloat(const char *s, const char *errprefix) {
	char *endp;
	double v = strtod(s, &endp);
	if (!s[0] || *endp) {
		std::cerr << errprefix << " '" << s << "'" << std::endl;
		usage();
		exit(1);
	}
	return v;
}

int64_t parseint(const char *s, const char *errprefix) {
	char *endp;
	int64_t v = strtoll(s, &endp, 10);
	if (!s[0] || *endp) {
		std::cerr << errprefix << " '" << s << "'" << std::endl;
		usage();
		exit(1);
	}
	return v;
}

int main(int argc, char **argv) {
	argv0 = argv[0];

	const int64_t BARWIDTH = 80;

	double low, high;
	bool havebounds;
	int64_t nbins = 10;

	if (argc == 1) {
		havebounds = false;
	} else if (argc == 2) {
		havebounds = false;
		nbins = parseint(argv[1], "Invalid number");
	} else if (argc == 3) {
		havebounds = true;
		low = parsefloat(argv[1], "Invalid number");
		high = parsefloat(argv[2], "Invalid number");
	} else if (argc == 4) {
		havebounds = true;
		low = parsefloat(argv[1], "Invalid number");
		high = parsefloat(argv[2], "Invalid number");
		nbins = parseint(argv[3], "Invalid number");
	} else {
		usage();
		return 1;
	}

	if (nbins < 1) {
		std::cerr << "histogram: Invalid number of bins '" << nbins << "'" << std::endl;
		usage();
		return 1;
	}

	if (havebounds && high <= low) {
		std::cerr << "histogram: high <= low" << std::endl;
		usage();
		return 1;
	}

	double minval = INFINITY, maxval = -INFINITY;
	std::vector<double> values;
	while (true) {
		double v;
		std::cin >> v;
		if (!std::cin) break;
		values.push_back(v);
		if (v < minval) minval = v;
		if (v > maxval) maxval = v;
	}
	if (!havebounds) {
		low = minval;
		high = maxval;
	}

	std::sort(values.begin(), values.end());

	std::vector<int64_t> histogram(nbins);

	int64_t binidx = 0, tally = 0, maxtally = -1;
	for (double v : values) {
		if (v < low || v > high) {
			// cerr << "Point " << v << " out of range!" << endl;
			continue;
		}
		int64_t bin = (v - low) / (high - low) * nbins;
		if (bin == nbins) bin--;
		assert(bin >= 0 && bin < nbins);
		if (bin != binidx) {
			histogram[binidx] = tally;
			if (tally > maxtally) maxtally = tally;
			binidx = bin;
			tally = 0;
		}
		tally++;
	}
	histogram[binidx] = tally;
	if (tally > maxtally) maxtally = tally;

	if (maxtally == 0) {
		std::cerr << "histogram: No data in range" << std::endl;
		return 1;
	}

	char fullbar[BARWIDTH + 1];
	memset(fullbar, '#', BARWIDTH);
	fullbar[BARWIDTH] = '\0';
	char emptybar[BARWIDTH + 1];
	memset(emptybar, ' ', BARWIDTH);
	emptybar[BARWIDTH] = '\0';

	for (size_t i = 0; i < histogram.size(); i++) {
		int64_t tally = histogram[i];
		int64_t width = BARWIDTH * tally / maxtally;
		char terminator = ")]"[i == histogram.size() - 1];
		std::cout << fullbar + BARWIDTH - width << emptybar + width
		          << " [" << std::setw(11) << low + (double)i / nbins * (high - low) << " - "
			      << std::setw(11) << low + (double)(i + 1) / nbins * (high - low) << terminator
		          << " [" << tally << "]" << std::endl;
	}
}