信息论上学习了fano编码，所以就尝试着自己写一遍fano编码

#include "iostream"
#include <fstream>
#include "map"
#include "string"
#include "math.h"
using namespace std;


multimap<float, pair<string, string>> W;

void show(multimap<float, pair<string, string>> word);

typedef decltype(W.begin()) map_pointer;

int initial(string file_name, int max){
	float probability = 0, temp = 0;
	string str = "";
	ifstream infile;
	infile.open(file_name, ios::in);
	for (int i = 0; i < max; ++i){
		infile >> temp >> str;
		probability += temp;
		W.insert({ temp, make_pair(str, "") });
	}
	if ((probability - 1) < 0.0001){
		return 1;
	}else{
		cout << "Sum of probability != 1" << endl;
		return 0;
	}
}

int make_code(map_pointer high_pointer, map_pointer low_pointer){
	float high_value = high_pointer->first, low_value = low_pointer->first;
	auto hp = high_pointer, lp = low_pointer;
	hp->second.second += "1";
	lp->second.second += "0";
	while (1){
		if (++hp == lp){//can not hp + 1
			--hp;
			if (hp != high_pointer){
				make_code(high_pointer, hp);
			}
			if (lp != low_pointer){
				make_code(lp, low_pointer);
			}
			return 1;
		}else if (high_value >= low_value){
			--hp;
			--lp;
			low_value += lp->first;
			lp->second.second += "0";
		}else{
			--hp;
			++hp;
			high_value += hp->first;
			hp->second.second += "1";
		}
	}
}

void show(multimap<float, pair<string, string>> word){
	ofstream Outfile;
	Outfile.open("text.txt", ios::out);
	Outfile << "***********************************************************" << endl;
	for (auto &m : word){
		Outfile << m.second.first << "\t" << m.second.second << endl;
		cout << m.second.first << "\t" << m.second.second << endl;
	}
}

int main(){
	initial("probability_68.txt", 68);
	if (make_code(W.begin(), --W.end())){
		show(W);
	}else{
		cout << "error" << endl;
	}
	system("pause");
}

需要注意的地方是，initial函数初始化时读取的text文本请按以下格式

最后上传一个68个字符概率的文件（空格用下划线_代替）

0.02	_
0.012	,
0.009	.
0.0037	?
0.0009	;
0.0031	!
0.00029	A
0.0014	B
0.00072	C
0.0009	D
0.0006	E
0.00071	F
0.0037	G
0.00051	H
0.00032	I
0.001	J
0.00081	K
0.00022	L
0.00021	M
0.00023	N
0.00024	O
0.00002	P
0.00038	Q
0.0002	R
0.0005	S
0.0007	T
0.00027	U
0.00003	V
0.0008	W
0.0017	X
0.0003	Y
0.0019	Z
0.064	a
0.013	b
0.0061	c
0.0246	d
0.0663	e
0.0111	f
0.0913	g
0.0555	h
0.09	i
0.02173	j
0.002	k
0.0064	l
0.0084	m
0.1254	n
0.07	o
0.0068	p
0.0059	q
0.0083	r
0.0219	s
0.0172	t
0.0936	u
0.00001	v
0.017	w
0.009	x
0.054	y
0.03	z
0.00131	0
0.00131	1
0.00131	2
0.00131	3
0.00131	4
0.00131	5
0.00131	6
0.00131	7
0.00131	8
0.00131	9