在横坐标上 从n点走到k点 至少要几步 可以到 n+1 n-1 n*2这3个点
Sample Input
5 17
Sample Output
4
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 #include <queue> 5 using namespace std; 6 7 int n , k ; 8 int ans ; 9 bool v[100010] ; 10 11 struct node 12 { 13 int x ; 14 int step ; 15 }; 16 17 bool yes(int x) 18 { 19 if (x>=0 && x<= 100010 && v[x] == 0) 20 return 1 ; 21 else 22 return 0 ; 23 } 24 25 int bfs() 26 { 27 queue<node> q ; 28 node now , t ; 29 now.x = n ; 30 now.step = 0 ; 31 q.push(now) ; 32 memset(v , 0 , sizeof(v)) ; 33 v[n] = 1 ; 34 while(!q.empty()) 35 { 36 now = q.front() ; 37 q.pop() ; 38 if (now.x == k) 39 return now.step ; 40 t.x = now.x + 1 ; 41 if (yes(t.x)) 42 { 43 t.step = now.step + 1 ; 44 q.push(t) ; 45 v[t.x] = 1 ; 46 } 47 t.x = now.x - 1 ; 48 if (yes(t.x)) 49 { 50 t.step = now.step + 1 ; 51 q.push(t) ; 52 v[t.x] = 1 ; 53 } 54 t.x = now.x * 2 ; 55 if (yes(t.x)) 56 { 57 t.step = now.step + 1 ; 58 q.push(t) ; 59 v[t.x] = 1 ; 60 } 61 62 } 63 return 0 ; 64 } 65 66 int main () 67 { 68 69 while (scanf("%d %d" , &n , &k) != EOF) 70 { 71 72 ans = bfs() ; 73 printf("%d " , ans) ; 74 } 75 76 return 0 ; 77 }