c++ 實現變進制數

#include <iostream>
#include <memory>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
#define MAXN 100001
#define ull unsigned long long
ull nums[MAXN];
bool used[MAXN];
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int N;
	ull M;
	cin >> N >> M;
	/* 變進制數初始化 */
	for (int i = 0; i < N; ++i) {
		cin >> nums[i];
		int k = 0;
		for (int j = 0; j < nums[i]; ++j) {
			if (used[j]) {
				continue;
			}
			++k;
		}
		used[nums[i] - 1] = true;
		nums[i] = k - 1;
	}
	/* 加上M */
	ull carry = M;
	for (int i = N - 2; i >= 0; --i) {
		nums[i] += carry;
		int base = N - i;
		carry = nums[i] / base;
		nums[i] %= base;
	}
	/* 再變回來 */
	memset(used, false, sizeof(used));
	for (int i = 0; i < N; ++i) {
		int j = 0;
		for (int k = 0; j < N && k <= nums[i]; ++j) {
			if (used[j]) {
				continue;
			}
			++k;
		}
		used[j - 1] = true;
		if (N - 1 == i) {
			cout << j << endl;
		}
		else {
			cout << j << ' ';
		}
	}
	return 0;
}

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