京东2019春招算法工程师笔试题 还原

  1 #include <bits/stdc++.h>
  2 using namespace std;
  3  
  4 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  5 #define Rep(i,n) for (int i = 0; i < (n); ++i)
  6 #define For(i,s,t) for (int i = (s); i <= (t); ++i)
  7 #define rFor(i,t,s) for (int i = (t); i >= (s); --i)
  8 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
  9 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
 10 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
 11 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)
 12  
 13 #define pr(x) cout << #x << " = " << x << "  "
 14 #define prln(x) cout << #x << " = " << x << endl
 15  
 16 #define LOWBIT(x) ((x)&(-x))
 17  
 18 #define ALL(x) x.begin(),x.end()
 19 #define INS(x) inserter(x,x.begin())
 20  
 21 #define ms0(a) memset(a,0,sizeof(a))
 22 #define msI(a) memset(a,inf,sizeof(a))
 23 #define msM(a) memset(a,-1,sizeof(a))
 24 
 25 #define MP make_pair
 26 #define PB push_back
 27 #define ft first
 28 #define sd second
 29  
 30 template<typename T1, typename T2>
 31 istream &operator>>(istream &in, pair<T1, T2> &p) {
 32     in >> p.first >> p.second;
 33     return in;
 34 }
 35  
 36 template<typename T>
 37 istream &operator>>(istream &in, vector<T> &v) {
 38     for (auto &x: v)
 39         in >> x;
 40     return in;
 41 }
 42  
 43 template<typename T1, typename T2>
 44 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
 45     out << "[" << p.first << ", " << p.second << "]" << "\n";
 46     return out;
 47 }
 48 
 49 inline int gc(){
 50     static const int BUF = 1e7;
 51     static char buf[BUF], *bg = buf + BUF, *ed = bg;
 52     
 53     if(bg == ed) fread(bg = buf, 1, BUF, stdin);
 54     return *bg++;
 55 } 
 56 
 57 inline int ri(){
 58     int x = 0, f = 1, c = gc();
 59     for(; c<48||c>57; f = c==‘-‘?-1:f, c=gc());
 60     for(; c>47&&c<58; x = x*10 + c - 48, c=gc());
 61     return x*f;
 62 }
 63  
 64 typedef long long LL;
 65 typedef unsigned long long uLL;
 66 typedef pair< double, double > PDD;
 67 typedef pair< int, int > PII;
 68 typedef pair< string, int > PSI;
 69 typedef set< int > SI;
 70 typedef vector< int > VI;
 71 typedef vector< PII > VPII;
 72 typedef map< int, int > MII;
 73 typedef pair< LL, LL > PLL;
 74 typedef vector< LL > VL;
 75 typedef vector< VL > VVL;
 76 const double EPS = 1e-10;
 77 const LL inf = 0x7fffffff;
 78 const LL infLL = 0x7fffffffffffffffLL;
 79 const LL mod = 998244353;
 80 const int maxN = 1e4 + 7;
 81 const LL ONE = 1;
 82 const LL evenBits = 0xaaaaaaaaaaaaaaaa;
 83 const LL oddBits = 0x5555555555555555;
 84 
 85 int n, a[maxN]; 
 86 // dp[x][y][z]表示x位置的后一个元素为y，再后一个元素为z，这种情况下前x+2长度一共有多少种 
 87 LL dp[2][207][207];
 88 LL ans = 0;
 89 
 90 void add_mod(LL &a, LL b) {
 91     a = (a + b) % mod;
 92 }
 93 
 94 /*
 95 // x：当前处理到的位置
 96 // y：第 x + 1 位置元素的值 
 97 // z：第 x + 2 位置元素的值 
 98 unordered_map< LL, int > dp;
 99 inline LL dfs(LL x, int y, int z) {
100     if(x == 0) return y <= max(z, a[x]);
101     LL tmp = (x << 16) + (y << 8) + z;
102     if(dp.find(tmp) != dp.end()) return dp[tmp];
103     LL ret = 0;
104     int s = 1, t = 200
105     if(a[x]) s = t = a[x];
106     
107     For(i, s, t) if(y <= max(z, i)) add_mod(ret, dfs(x - 1, i, y));
108     
109     return dp[tmp] = ret % mod;
110 }
111 */
112 
113 
114 
115 int main(){
116     INIT(); 
117     cin >> n;
118     For(i, 1, n) cin >> a[i];
119     a[0] = 1;
120     For(y, 1, 200) For(z, 1, 200) dp[0][y][z] = y <= max(z, a[0]);
121     
122     int now = 0;
123     For(x, 1, n) {
124         now = !now;
125         ms0(dp[now]);
126         For(y, 1, 200) {
127             For(z, 1, 200) {
128                 int s = 1, t = 200;
129                 if(a[x]) s = t = a[x];
130                 For(i, s, t) if(y <= max(z, i)) add_mod(dp[now][y][z], dp[!now][i][y]);
131             }
132         }
133     }
134     
135     cout << dp[now][1][1] << endl;
136     return 0;
137 }