HDU 4576 简单概率 + 滚动数组DP（大坑）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4576

坑大发了，居然加 % 也会超时；

 #include <cstdio>
 #include <iostream>
 #include <sstream>
 #include <cmath>
 #include <cstring>
 #include <cstdlib>
 #include <string>
 #include <vector>
 #include <map>
 #include <set>
 #include <queue>
 #include <stack>
 #include <algorithm>
 using namespace std;
 #define ll long long
 #define _cle(m, a) memset(m, a, sizeof(m))
 #define repu(i, a, b) for(int i = a; i < b; i++)
 #define repd(i, a, b) for(int i = b; i >= a; i--)
 #define sfi(n) scanf("%d", &n)
 #define sfl(n) scanf("%I64d", &n)
 #define pfi(n) printf("%d\n", n)
 #define pfl(n) printf("%I64d\n", n)
 #define MAXN 1000005
 int n, l, m, r, d;
 int t = , mm;
 double dp[][];
 int main()
 {
     while(~scanf("%d%d%d%d", &n, &m, &l, &r) && (n + m + l + r))
     {
         t = ;
         repu(i, , n + ) dp[][i] = 0.0;
         dp[][] = 1.0;
         int c;
         repu(i, , m)
         {
             sfi(d);
             if(l ==  && r == n) continue;
             c = d / n;
             mm = d - n * c;
             if(mm)
             {
                 t = !t;
                 repu(j, , n + )
                 {
                     int lt, rt;
                     if((n + (j - mm)) >= n) lt = (n + (j - mm)) - n;
                     else lt = (n + (j - mm));
                     if((j + mm) >= n) rt = (j + mm) - n;
                     else rt = (j + mm);
                     if(lt == ) lt = n;
                     if(rt == ) rt = n;
                     dp[t][j] = (dp[!t][lt] + dp[!t][rt]) / 2.0;
                     //cout<<j<<" :"<<dp[t][j]<<endl;
                 }
             }
         }
         double ans = 0.0;
         if(l ==  && r == n) ans = 1.0;
         else
         repu(i, l, r + ) ans += dp[t][i];
         printf("%.4lf\n", ans);
     }
     return ;
 }

AC

 #include <cstdio>
 #include <iostream>
 #include <sstream>
 #include <cmath>
 #include <cstring>
 #include <cstdlib>
 #include <string>
 #include <vector>
 #include <map>
 #include <set>
 #include <queue>
 #include <stack>
 #include <algorithm>
 using namespace std;
 #define ll long long
 #define _cle(m, a) memset(m, a, sizeof(m))
 #define repu(i, a, b) for(int i = a; i < b; i++)
 #define repd(i, a, b) for(int i = b; i >= a; i--)
 #define sfi(n) scanf("%d", &n)
 #define sfl(n) scanf("%I64d", &n)
 #define pfi(n) printf("%d\n", n)
 #define pfl(n) printf("%I64d\n", n)
 #define MAXN 1000005
 int n, l, m, r, d;
 int t = , mm;
 double dp[][];
 int main()
 {
     while(~scanf("%d%d%d%d", &n, &m, &l, &r) && (n + m + l + r))
     {
         t = ;
         repu(i, , n + ) dp[][i] = 0.0;
         dp[][] = 1.0;
         int c;
         repu(i, , m)
         {
             sfi(d);
             if(l ==  && r == n) continue;
             c = d / n;
             mm = d - n * c;
             if(mm)
             {
                 t = !t;
                 repu(j, , n + )
                 {
                     int lt, rt;
                     lt = (n + (j - mm)) % n;
                     rt = (j + mm) % n;
 //                    if((n + (j - mm)) >= n) lt = (n + (j - mm)) - n;
 //                    else lt = (n + (j - mm));
 //                    if((j + mm) >= n) rt = (j + mm) - n;
 //                    else rt = (j + mm);
                     if(lt == ) lt = n;
                     if(rt == ) rt = n;
                     dp[t][j] = (dp[!t][lt] + dp[!t][rt]) / 2.0;
                     //cout<<j<<" :"<<dp[t][j]<<endl;
                 }
             }
         }
         double ans = 0.0;
         if(l ==  && r == n) ans = 1.0;
         else
         repu(i, l, r + ) ans += dp[t][i];
         printf("%.4lf\n", ans);
     }
     return ;
 }

TLE

% 慎用啊必须，虽然不知道为什么