[C++知识库]#113. 可重排列

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

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define mset(s,t) memset(s,t,sizeof(t))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define mp make_pair

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;   
typedef vector<ll> Vll;               
typedef vector<pair<int, int> > vpii;
typedef vector<pair<ll, ll> > vpll;                        

const ll mod = 1e9 + 7;
//const ll mod = 998244353;
const double pi  = acos(-1.0);

inline ll qmi (ll a, ll b) {
	ll ans = 1;
	while (b) {
		if (b & 1) ans = ans * a%mod;
		a = a * a %mod;
		b >>= 1;
	}
	return ans;
}
inline int read () {
	int x = 0, f = 0;
	char ch = getchar();
	while (!isdigit(ch)) f |= (ch=='-'),ch= getchar();
	while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
	return f?-x:x;
}
template<typename T> void print(T x) {
	if (x < 0) putchar('-'), x = -x;
	if (x >= 10) print(x/10);
	putchar(x % 10 + '0');
}
inline ll sub (ll a, ll b) {
	return ((a - b ) %mod + mod) %mod;
}
inline ll add (ll a, ll b) {
	return (a + b) %mod;
}
inline ll inv (ll a) {
	return qmi(a, mod - 2);
}
bool st[10100];
int n, m;
int cnt[10];
vector<int> ans, p;
map<string,int> vis;
void dfs(int u) {
	if (u== m) {
		string s = "";
		for (auto t : ans)
			s += to_string(t);
		
		if (vis[s]) return;
		vis[s] = 1;
		for (auto t : ans) {
			cout << t << ' ';
		}
		puts("");
		return;
	}	
	for (int j = 1; j <= n; j ++) {
		if (!cnt[j]) continue;
		
		cnt[j] -= 1;
		ans.pb(j);
		
		dfs(u + 1);
		
		ans.pop_back();
		cnt[j] += 1;
	}
}
void solve() {
	cin >> n ;
	for (int i =1; i <= n; i ++)
		{
			cin >> cnt[i];
			for (int j = 1; j <= cnt[i]; j ++)
				p.pb(i);
			m += cnt[i];
		}
	dfs(0);
}
int main () {
	// ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
    int t;
    t =1;
    
    while (t --) solve();
    return 0;
}

直接把所有要用到的数加进来的排法会超时