999C Alphabetic Removals
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:
- if there is at least one letter 'a', remove the leftmost occurrence and stop the algorithm, otherwise go to next item;
- if there is at least one letter 'b', remove the leftmost occurrence and stop the algorithm, otherwise go to next item;
- ...
- remove the leftmost occurrence of the letter 'z' and stop the algorithm.
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.
Input
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.
Output
Print the string that will be obtained from ss after Polycarp removes exactly kkletters 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).
Examples
Input
15 3 cccaabababaccbc
Output
cccbbabaccbc
Input
15 9 cccaabababaccbc
Output
cccccc
題解:先統計每個字元的個數,然後從a開始確定刪除哪些字元,如果有字元一部分刪除一部分不刪除的,那前面的刪除,記錄一下就可以了
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=4e5+10;
int n,m,len;
char s[N];
int a[26],vis[26];
int main()
{
while(~scanf("%d%d",&n,&m))
{
memset(a,0,sizeof(a));
scanf("%s",s);
for(int i=0;i<n;i++)
{
a[s[i]-'a']++;
}
int maxx=-1,flag=0;
for(int i=0;i<26;i++)
{
if(a[i]<=m) maxx=i,m-=a[i];
else
{
flag=m;
break;
}
if(m==0) break;
}
for(int i=0;i<n;i++)
{
if(s[i]-'a'<=maxx) continue;
if(s[i]-'a'==maxx+1)
{
if(flag) flag--;
else cout<<s[i];
}
if(s[i]-'a'>maxx+1) printf("%c",s[i]);
}
cout<<endl;
}
return 0;
}