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OI-codes/S2OJ/1024/1024.cpp

45 lines
941 B
C++

#include <bits/stdc++.h>
using namespace std;
int n, k, p, trie[10000005][2], size[10000005];
char s[100005];
bool a[100005];
void calcsize(int u) {
if (trie[u][0]) calcsize(trie[u][0]);
if (trie[u][1]) calcsize(trie[u][1]);
size[u] += size[trie[u][0]] + size[trie[u][1]];
}
void print(int u, int k) {
if (u != 1 && k-- == 1) {
cout << endl;
exit(0);
}
if (size[trie[u][0]] >= k) {
cout << 0;
print(trie[u][0], k);
} else {
cout << 1;
print(trie[u][1], k - size[trie[u][0]]);
}
}
int main() {
cin >> n >> k >> s + 1;
for (int i = 1; i <= n; i++) {
a[i] = s[i] - '0';
}
p = 1;
for (int i = 1; i <= n; i++) {
int u = 1;
for (int j = i; j <= min(n, i + k - 1); j++) {
size[u = (trie[u][a[j]] ? trie[u][a[j]] : trie[u][a[j]] = ++p)] = 1;
}
}
calcsize(1);
print(1, k);
return 0;
}