lab.cpp

#include <iostream>
#include <map>
#include <string>
using namespace std;



int main(){
	map<char, long double> abc;
	map<char, long double> lows;
	string msg;
	
	cout<<"msg>";
	getline(cin,msg);

	int len = msg.length();

	for(auto i = 0; i < len; i++){
		abc[msg[i]] += 1.0 / len;
	}

	long double code = 0.0, high = 1.0, low = 0.0, r = 0.0;
	long double l, h = 0.0, highRange, lowRange, range;
	char c;
	string decoded;

	for(auto i: abc){
		l = h;
		h += i.second;
		lows[i.first] = l;
		//printf("%c  %4.2LF  %4.2LF - %4.2LF\n",i.first, i.second, l, h);
	}

	for(auto c: msg){
		
		lowRange = lows[c];
		highRange = lowRange + abc[c];

		range = high - low;
		high = low + range * highRange;
		low = low + range * lowRange;

		printf("%c %12.14LF   %12.14LF\n", c, low, high);

	}

	code = low;
	cout<<endl;

	while(--len >= 0){

		for(auto i: lows){
			if(i.second <= code && code < i.second + abc[i.first]){
				c = i.first;
				lowRange = i.second;
				range = abc[c];
				decoded += c;
				break;
			}
		}
		printf("%c %12.14LF\n",c,code);
		code = (code - lowRange) / range;
	}

	cout<<decoded<<endl;

	return 0;
}