[HDOJ5898]odd-even number（数位dp）

  1 #include <bits/stdc++.h>
  2 using namespace std;
  3 #define fr first
  4 #define sc second
  5 #define cl clear
  6 #define BUG puts("here!!!")
  7 #define W(a) while(a--)
  8 #define pb(a) push_back(a)
  9 #define Rint(a) scanf("%d", &a)
 10 #define Rll(a) scanf("%I64d", &a)
 11 #define Rs(a) scanf("%s", a)
 12 #define Cin(a) cin >> a
 13 #define FRead() freopen("in", "r", stdin)
 14 #define FWrite() freopen("out", "w", stdout)
 15 #define Rep(i, len) for(int i = 0; i < (len); i++)
 16 #define For(i, a, len) for(int i = (a); i < (len); i++)
 17 #define Cls(a) memset((a), 0, sizeof(a))
 18 #define Clr(a, x) memset((a), (x), sizeof(a))
 19 #define Full(a) memset((a), 0x7f7f7f, sizeof(a))
 20 #define lrt rt << 1
 21 #define rrt rt << 1 | 1
 22 #define pi 3.14159265359
 23 #define RT return
 24 #define lowbit(x) x & (-x)
 25 #define onecnt(x) __builtin_popcount(x)
 26 typedef long long LL;
 27 typedef long double LD;
 28 typedef unsigned long long ULL;
 29 typedef pair<int, int> pii;
 30 typedef pair<string, int> psi;
 31 typedef pair<LL, LL> pll;
 32 typedef map<string, int> msi;
 33 typedef vector<int> vi;
 34 typedef vector<LL> vl;
 35 typedef vector<vl> vvl;
 36 typedef vector<bool> vb;
 37 
 38 const int maxn = 19;
 39 int digit[maxn];
 40 LL l, r;
 41 LL dp[maxn][2][2][2];
 42 
 43 LL dfs(int l, int pre, int con, bool fz, bool flag) {
 44   if(l == 0) {
 45     if(pre % 2 == 0) {
 46       if(con % 2 == 0) return 0;
 47       if(con % 2 == 1) return 1;
 48     }
 49     else {
 50       if(con % 2 == 0) return 1;
 51       if(con % 2 == 1) return 0;
 52     }
 53   }
 54   if(!flag && ~dp[l][pre][con][fz]) return dp[l][pre][con][fz];
 55   LL ret = 0;
 56   int pos = flag ? digit[l] : 9;
 57   if(fz) {
 58     Rep(i, pos+1) {
 59       ret += dfs(l-1, i%2, 1, fz&&(i==0), flag&&(i==pos));
 60     }
 61   }
 62   else if((pre + con) % 2 == 1) {
 63     Rep(i, pos+1) {
 64       if((i + pre) % 2 == 0) {
 65         ret += dfs(l-1, i%2, (con+1)%2, fz&&(i==0), flag&&(i==pos));
 66       }
 67       else {
 68         ret += dfs(l-1, i%2, 1, fz&&(i==0), flag&&(i==pos));
 69       }
 70     }
 71   }
 72   else {
 73     Rep(i, pos+1) {
 74       if((i + pre) % 2 == 0) {
 75         ret += dfs(l-1, i%2, (con+1)%2, fz&&(i==0), flag&&(i==pos));
 76       }
 77     }
 78   }
 79   if(!flag) dp[l][pre][con][fz] = ret;
 80   return ret;
 81 }
 82 
 83 LL f(LL x) {
 84   int pos = 0;
 85   while(x) {
 86     digit[++pos] = x % 10;
 87     x /= 10;
 88   }
 89   return dfs(pos, 0, 1, true, true);
 90 }
 91 
 92 signed main() {
 93   //FRead();
 94   int T, _ = 1;
 95   Rint(T);
 96   Clr(dp, -1);
 97   W(T) {
 98     cin >> l >> r;
 99     printf("Case #%d: ", _++);
100     cout << f(r) - f(l-1) << endl;
101   }
102   RT 0;
103 }