给出一个字符串，我想根据其字符减少的频率对其进行排序。 如果计数相同，则字符应按字母顺序排序。
brew cask reinstall intellij-idea-ce到目前为止，这是我的代码：
function substring(string,start,end) {
var result = '',length = Math.min(string.length,end),i = start;
while (i < length) result += string[i++];
return result;
}
console.log(substring('This is a string',4));
console.log(substring('This is a string',40,4));在Objects.keys（map）.sort（）语句的开头出现“意外令牌”错误。我一生无法弄清楚哪里出了问题。
对于此问题的任何帮助或见解，将不胜感激。
一种实现方法是利用语言功能，例如：
let str = "Lorem ipsum dolor sit amet,Consectetur adipiscing elit,"
let newStr =
str.split('').sort().join('').match(/(\w)\1*/g).sort(
(x,y) => y.length - x.length
).join('')
console.log(newStr)
将字符串splits放入数组，按值sorts将其joins放入正则表达式/(\w)\1*/g的字符串matched中返回具有所有字符组的数组。反过来，该数组按其元素的长度排序，然后再次连接为字符串。
用C ++解决
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
struct Node
{
char ch;
int total;
Node(char ch,int total){
this->ch = ch;
this->total = total;
}
};
bool mySort(Node a,Node b){
if(a.total == b.total){
return a.ch < b.ch;
}
return (a.total > b.total);
}
std::string solve(std::string &s){
std::vector<Node> nodes;
std::map<char,int> m;
for (int i = 0; i < s.size(); ++i)
{
std::map<char,int>::iterator it = m.find(s[i]);
if(it != m.end()){
// Exists
Node *node = &nodes[it->second];
node->total++;
}else{
Node node(s[i],1);
nodes.push_back(node);
m[s[i]] = nodes.size() - 1;
}
}
std::sort(nodes.begin(),nodes.end(),mySort);
std::string str = "";
for (int i = 0; i < nodes.size(); ++i)
{
for (int j = 0; j < nodes[i].total; ++j)
{
str += nodes[i].ch;
}
}
return str;
}
int main()
{
std::string s = "Programming";
std::string result = solve(s);
std::cout << "Result is: " << result;
return 0;
}
对于JavaScript
var s = "Programming";
var map = {};
var nodes = [];
for(var i = 0; i < s.length; ++i){
var it = map[s[i]];
if(typeof it !== "undefined"){
//exist
nodes[it].total ++;
}else{
map[s[i]] = nodes.length;
nodes.push({total: 1,ch: s[i]});
}
}
nodes = nodes.sort(function(a,b){
if(a.total < b.total){
return 1;
}
if(a.total == b.total){
if(a.ch < b.ch){
return -1;
}else{
return 1;
}
}
return 0;
});
var result = "";
for(var i =0; i < nodes.length; ++i){
var node = nodes[i];
for(var j = 0; j < node.total; ++j){
result += node.ch;
}
}
console.log(result);