You are given a string ss consisting of nn lowercase Latin letters. Polycarp wants to remove exactly kk characters (k≤nk≤n) from the string ss. Polycarp uses the following algorithm kk times:
This algorithm removes a single letter from the string. Polycarp performs this algorithm exactly kk times, thus removing exactly kk characters.
Help Polycarp find the resulting string.
The first line of input contains two integers nn and kk (1≤k≤n≤4?1051≤k≤n≤4?105) — the length of the string and the number of letters Polycarp will remove.
The second line contains the string ss consisting of nn lowercase Latin letters.
Print the string that will be obtained from ss after Polycarp removes exactly kk letters using the above algorithm kk times.
If the resulting string is empty, print nothing. It is allowed to print nothing or an empty line (line break).
15 3
cccaabababaccbc
cccbbabaccbc
15 9
cccaabababaccbc
cccccc
1 1
u
#include<bits/stdc++.h> using namespace std; int n; string str; int k; vector<int> cnt(26); int main() { cin>>n>>k; cin>>str; for(int i=0; i<n; i++) { cnt[str[i]-‘a‘]++; } //记录下每个字母的数量 //从a开始减去存在的字母 //如果没有了 就记录下还可以输出的字母 int pos=26; for(int i=0; i<26; i++) { if(k>=cnt[i]) { k-=cnt[i]; } else { pos=i; break; } } string ans; int rem=k; for(int i=0; i<n; i++) { int cur=str[i]-‘a‘; //在pos后面的字母可以用 //用完了k的字母可以用 if(cur>pos||(cur==pos&&rem==0)) { ans+=str[i]; } else if(cur==pos) { rem--; } } cout<<ans<<endl; return 0; }
code forces 999C Alphabetic Removals
原文：https://www.cnblogs.com/buerdepepeqi/p/9216842.html
