思路：
dp。
实现：
1 #include <bits/stdc++.h> 2 using namespace std; 3 int a[100005], dp[100005][6]; 4 int main() 5 { 6 int n; 7 while (cin >> n) 8 { 9 for (int i = 1; i <= n; i++) cin >> a[i]; 10 memset(dp, 0, sizeof dp); 11 for (int i = 1; i <= 5; i++) dp[1][i] = 1; 12 for (int i = 2; i <= n; i++) 13 { 14 for (int j = 1; j <= 5; j++) 15 { 16 if (a[i] > a[i - 1]) 17 { 18 for (int k = 1; k < j; k++) 19 { 20 if (dp[i - 1][k]) dp[i][j] = k; 21 } 22 } 23 else if (a[i] < a[i - 1]) 24 { 25 for (int k = j + 1; k <= 5; k++) 26 { 27 if (dp[i - 1][k]) dp[i][j] = k; 28 } 29 } 30 else 31 { 32 for (int k = 1; k <= 5; k++) 33 { 34 if (k != j && dp[i - 1][k]) dp[i][j] = k; 35 } 36 } 37 } 38 } 39 bool flg = false; 40 int i = 1; 41 for ( ; i <= 5; i++) 42 { 43 if (dp[n][i]) { flg = true; break; } 44 } 45 if (!flg) cout << "-1" << endl; 46 else 47 { 48 vector<int> v; 49 v.push_back(i); 50 int now = n; 51 while (now >= 2) 52 { 53 v.push_back(dp[now][i]); 54 i = dp[now][i]; 55 now--; 56 } 57 for (int i = v.size() - 1; i >= 0; i--) cout << v[i] << " "; 58 cout << endl; 59 } 60 } 61 return 0; 62 }