TZOJ 4493: Remove Digits

4493: Remove Digits

时间限制(普通/Java):1000MS/3000MS     内存限制:65536KByte
总提交: 329            测试通过:77

描述

Given an N-digit number, you should remove K digits and make the new integer as large as possible.

输入

The first line has two integers N and K (1 ≤ K<N≤500000).
The next line has a N-digit number with no leading zero.

输出

Output the largest possible integers by removing K digits.

样例输入

4 2 2835

样例输出

85

 

#include <bits/stdc++.h>
using namespace std;
char s[500005];
int main()
{
    ios::sync_with_stdio(false);
    int n,k,num=0;
    char c;
    s[0]='9';
    cin>>n>>k;
    for(int i=0;i<n;i++){
        cin>>c;
       while(c>s[num]){
            if(!k||!num) break;
            num--,k--;
       }
        s[++num]=c;
   }
    if(k)
        num=num-k;
    s[++num]='\0';
    cout << s+1 << endl;
    return 0;
}