Look-and-say sequence is a sequence of integers as the following:
D, D1, D111, D113, D11231, D112213111, ...
where D
is in [0, 9] except 1. The (n+1)st number is a kind of description of the nth number. For example, the 2nd number means that there is one D
in the 1st number, and hence it is D1
; the 2nd number consists of one D
(corresponding to D1
) and one 1 (corresponding to 11), therefore the 3rd number is D111
; or since the 4th number is D113
, it consists of one D
, two 1's, and one 3, so the next number must be D11231
. This definition works for D
= 1 as well. Now you are supposed to calculate the Nth number in a look-and-say sequence of a given digit D
.
Input Specification:
Each input file contains one test case, which gives D
(in [0, 9]) and a positive integer N (≤ 40), separated by a space.
Output Specification:
Print in a line the Nth number in a look-and-say sequence of D
.
Sample Input:
1 8
Sample Output:
1123123111
思路
为了求第n+1个,要对第n个进行遍历。对于每一个遍历到的数字,首先把该数字保存,然后计数该数字连续相同的个数。
把个数也保存当这个遍历结束的时候,第n+1个就求出来了。
#include<iostream> #include<vector> #include<algorithm> #include<queue> #include<string> #include<map> #include<set> #include<stack> using namespace std; int main() { int d,n; cin>>d>>n; vector<int> temp; temp.push_back(d); vector<int>print; for(int i=0;i<n-1;i++) { for(int j=0;j<temp.size();) { int m=j,coun=0; print.push_back(temp[j]); while(m<temp.size()) { if(temp[m]==temp[j]) { m++; coun++; } else break; } j=m; print.push_back(coun); } temp=print; print.clear(); } print=temp; for(auto it:print) cout<<it; return 0; }