C++(clang++ 11.0.1) 解法, 执行用时: 659ms, 内存消耗: 12108K, 提交时间: 2023-01-20 21:25:10

#include <bits/stdc++.h>
using namespace std;

char s[20] = "0123456789abcdef";
int cnt, k;
bool dp[22][17][17][17][17][17];
array<int, 7> tmp, v, C[22];

void dfs1 (int t, int d) {
	if (d >= 5) { C[cnt++] = tmp; return ;}
	for (int i = t; i < 7; i++) {
		tmp[d] = i;
		dfs1 (i + 1, d + 1);
	}
}

void dfs2 (int d) {
	if (k == 0) return ;
	if (d >= 7) {
		for (int i = 0; i < cnt; i++) {
			if(dp[i][tmp[C[i][0]]][tmp[C[i][1]]][tmp[C[i][2]]][tmp[C[i][3]]][tmp[C[i][4]]]) return ;
		}
		for (int i = 0; i < cnt; i++) {
			dp[i][tmp[C[i][0]]][tmp[C[i][1]]][tmp[C[i][2]]][tmp[C[i][3]]][tmp[C[i][4]]] = 1;
		}
		if (--k == 0) {
			for (int i = 0; i < 7; i++)
				cout << s[tmp[i]];
		}
		return ;
	}
	for (int i = 0; i < 16; i++) {
		tmp[d] = i;
		dfs2 (d + 1);
	}
}

void solve() {
	cin >> k;
	dfs1 (0, 0);
	dfs2 (0);
}

signed main() {
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}