杭电 hdu 1548 A strange lift

/* THE PROGRAM IS MADE BY PYY */ /*----------------------------------------------------------------------------// Copyright (c) 2011 panyanyany All rights reserved. URL : http://acm.hdu.edu.cn/showproblem.php?pid=1548 Name : 1548 A strange lift Date : Thursday, August 25, 2011 Time Stage : more than half an hour Result: 4492153 2011-08-25 19:42:55 Accepted 1548 31MS 400K 1680 B C++ pyy Test Data: Review: 单向的最短路（bfs也可以做），只是在制图的时候要注意，其他都跟普通的最短路一样了 //----------------------------------------------------------------------------*/ #include #include #include #define max(a, b) (((a) > (b)) ? (a) : (b)) #define min(a, b) (((a) < (b)) ? (a) : (b)) #define infinity 0x0f0f0f0f #define minus_inf 0x80808080 #define MAXSIZE 209 #define SafeAccess(x) (0 < (x) && (x) <= n) int n, s, e ; int map[MAXSIZE][MAXSIZE], used[MAXSIZE], dp[MAXSIZE] ; void dijkstra () { int i, j, iMinPath, MinPath ; memset (used, 0, sizeof (used)) ; for (i = 1 ; i <= n ; ++i) dp[i] = map[s][i] ; dp[s] = 0 ; for (i = 1 ; i <= n ; ++i) { MinPath = infinity ; iMinPath = 0 ; for (j = 1 ; j <= n ; ++j) if (!used[j] && dp[j] < MinPath) { iMinPath = j ; MinPath = dp[j] ; } used[iMinPath] = 1 ; for (j = 1 ; j <= n ; ++j) if (!used[j] && dp[iMinPath] + map[iMinPath][j] < dp[j]) { dp[j] = dp[iMinPath] + map[iMinPath][j] ; } } } int main () { int i, j ; while (scanf ("%d", &n), n) { scanf ("%d%d", &s, &e) ; memset (map, infinity, sizeof (map)) ; for (i = 1 ; i <= n ; ++i) { scanf ("%d", &j) ; // 注意不能越界 if (SafeAccess (i - j)) map[i][i-j] = 1 ; if (SafeAccess (i + j)) map[i][i+j] = 1 ; } dijkstra () ; if (infinity != dp[e]) printf ("%d\n", dp[e]) ; else // 一开始没怎么看题，把这句给忘了= =！ puts ("-1") ; } return 0 ; }