hdu1023 Train Problem II
结题思路很容易想到递归，用记忆化搜索方式寻找答案。
由于ans可能非常大，用c++需要自己写加法器。
acm.hdu.edu.cn/showproblem.php?pid=1023
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 5 using namespace std; 6 typedef __int64 LL; 7 const int maxn = 150 + 10; 8 char buffer[maxn * maxn][maxn]; 9 LL f[maxn][maxn]; 10 int n, N; 11 12 void add(int lhs, int rhs, int dest){ 13 int d = 0; 14 for(int i = maxn - 2; i >= 0; i--){ 15 int j = buffer[lhs][i] + buffer[rhs][i] + d; 16 buffer[dest][i] = j % 10; 17 d = j / 10; 18 } 19 } 20 21 int solve(int s, int q){ 22 if(f[s][q] != -1) return f[s][q]; 23 if(!q) return f[s][q] = 0; 24 if(s){ 25 int l1 = solve(s + 1, q - 1), l2 = solve(s - 1, q); 26 add(l1, l2, N); 27 N++; 28 return f[s][q] = N - 1; 29 } 30 return f[s][q] = solve(s + 1, q - 1); 31 } 32 33 void print(int i){ 34 int low = maxn - 1; 35 for(int j = 0; j < maxn - 1; j++){ 36 if(buffer[i][j]){ 37 low = j; 38 break; 39 } 40 } 41 for(int j = low; j < maxn - 1; j++) putchar(buffer[i][j] + '0'); 42 putchar('\n'); 43 } 44 45 int main(){ 46 memset(f, -1, sizeof f); 47 memset(buffer, 0, sizeof buffer); 48 buffer[0][maxn - 2] = 1; 49 N = 1; 50 while(~scanf("%d", &n)){ 51 int ans = solve(0, n); 52 print(ans); 53 } 54 return 0; 55 }
