POJ-3278 Catch That Cow
Description
Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K(0 ≤ K ≤ 100,000) on the same number line. Farmer John has two modes of transportation: walking and teleporting.
* Walking: FJ can move from any point X to the points X - 1 or X + 1 in a single minute
* Teleporting: FJ can move from any point X to the point 2 × X in a single minute.
If the cow, unaware of its pursuit, does not move at all, how long does it take for Farmer John to retrieve it?
Input
Line 1: Two space-separated integers: N and K
Output
Line 1: The least amount of time, in minutes, it takes for Farmer John to catch the fugitive cow.
Sample Input
5 17
Sample Output
4
大数组可以用vector
大数组可以用vector
大数组可以用vector
#include <iostream> #include <queue> #include <vector> using namespace std; int N, K; vector<int> data; int main(void) { int bfs(void); while(scanf("%d%d", &N, &K) != EOF) { for(int i = 0; i <= 2*K; i++) data.push_back(-1); if(K <= N) { printf("%d\n", N-K); continue; } else { int e = bfs(); printf("%d\n", e); } } return 0; } int bfs() { queue<int> que; int cas; data[N] = 0; cas = N; que.push(cas); while(que.size()) { int ca = que.front(); que.pop(); if(ca == K) break; for(int i = 0; i < 3; i++) { if(i == 0) cas = ca + 1; if(i == 1) cas = ca - 1; if(i==2) cas = ca * 2; if(cas >= 0 && cas <= 2*K && data[cas] < 0) { data[cas] = data[ca] + 1; que.push(cas); } } } return data[K]; }