【nowcoder-2017校招真题】保留最大的数

sta = []
num = '0123456789'

s = input()
n = m = int(input())

for i in s:
	while len(sta) != 0 and num.index(sta[-1]) < num.index(i) and m > 0:
		m -= 1
		sta.pop()
	sta.append(i)
	
print (''.join(sta[:(len(s) - n)]))

#include <bits/stdc++.h>

using namespace std;

queue <int> q[10];

char s[50010];

int n, m, len;

int main() {
    ios::sync_with_stdio(false);
    cin >> s >> m;
    len = strlen(s), n = len - m;
    for (int i = 0; i < len; i ++)
        q[s[i] - '0'].push(i);
    for (int c, k = 0, j = -1; k < n; k ++) {
        for (int i = 9; ~i; i --) {
            while (!q[i].empty() && q[i].front() <= j) q[i].pop();
            if (!q[i].empty() && m >= q[i].front() - j - 1) {
                c = '0' + i;
                m -= q[i].front() - j - 1;
                j = q[i].front();
                break;
            }
        }
        putchar(c);
    }
    return 0;
}