标签：void NPU invalid ever ber answer start lead 一个
Return all non-negative integers of length N such that the absolute difference between every two consecutive digits is K.
Note that every number in the answer must not have leading zeros except for the number 0 itself. For example, 01 has one leading zero and is invalid, but 0 is valid.
You may return the answer in any order.
Example 1:
Input: N = 3, K = 7
Output: [181,292,707,818,929]
Explanation: Note that 070 is not a valid number, because it has leading zeroes.
Example 2:
Input: N = 2, K = 1
Output: [10,12,21,23,32,34,43,45,54,56,65,67,76,78,87,89,98]
Note:
1 <= N <= 90 <= K <= 9
搜索题。两边搜索。注意Ｎ＝１的特别情况，这个时候都行。
class Solution {
private:
unordered_map<int,vector<int>> mp ;
public:
vector<int> numsSameConsecDiff(int N, int K) {
if(N == 1){
vector<int> ret;
for(int i=0; i<10; i++) ret.push_back(i);
return ret;
}
for(int i=0; i<10; i++){
int idx = i + K;
if(idx < 10) mp[i].push_back(idx);
idx = i - K;
if(!mp[i].empty() && mp[i][0] == idx) continue;// K等于1特殊情况
if(idx >= 0) mp[i].push_back(idx);
}
vector<int> ret;
for(int i=1; i<10; i++){
if(!mp.count(i)) continue;
helper(ret, N, i, 0);
}
return ret;
}
void helper(vector<int>& ret, int N, int start, int tmpval){
int tt = tmpval*10 + start;
if(to_string(tt).size() == N) {
ret.push_back(tt);
return;
}
if(!mp.count(start)) return ;
vector<int> choices = mp[start];
for(auto x : choices){
helper(ret, N, x, tt);
}
}
};
再贴一个yubowen大佬的解法
typedef long long ll;
typedef vector<int> VI;
typedef pair<int,int> PII;
#define REP(i,s,t) for(int i=(s);i<(t);i++)
#define FILL(x,v) memset(x,v,sizeof(x))
const int INF = (int)1E9;
#define MAXN 100005
class Solution {
public:
int N, K;
void solve(int i, int ld, int val, VI &ans) {
if (i == N) {
ans.push_back(val);
return;
}
REP(t,0,2) {
int d = t == 0 ? ld + K : ld - K;
if (K == 0 && t == 1) continue;
if (0 <= d && d <= 9) {
solve(i+1, d, val*10 + d, ans);
}
}
}
vector<int> numsSameConsecDiff(int _N, int _K) {
N = _N; K = _K;
VI ans;
if (N == 1) {
REP(i,0,10) ans.push_back(i);
return ans;
}
REP(s,1,10) solve(1, s, s, ans);
return ans;
}
};
LC 967. Numbers With Same Consecutive Differences
标签：void NPU invalid ever ber answer start lead 一个
原文地址：https://www.cnblogs.com/ethanhong/p/10200003.html
