HDU 3152 Obstacle Course (priority queue)

HDU 3152 Obstacle Course (priority queue)
Problem Description

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N* NSquare matrices contain the expenses for traversing each individual cell. for each of them, your task is to find the minimum-cost traversal from the top left cell [0] [0] to the bottom right cell [ N-1] [ N-1]. Legal moves are up, down, left, and right; that is, either the row index changes by one or the column index changes by one, but not both.

InputEach problem is specified by a single integer between 2 and 125 giving the number of rows and columns in N* NSquare matrix. The file is terminated by the case N= 0.

Following the specification NYou will find NLines, each containing NNumbers. These numbers will be given as single digits, zero through nine, separated by single blanks.

OutputEach problem set will be numbered (beginning at one) and will generate a single line giving the problem set and the expense of the minimum-cost path from the top left to the bottom right corner, exactly as shown in the sample output (with only a single space after "Problem" and after the colon ).

Sample Input

35 5 43 9 13 2 753 7 2 0 12 8 0 9 11 2 1 8 19 8 9 2 03 6 5 1 579 0 5 1 1 5 34 1 2 1 6 5 30 7 6 1 6 8 51 1 7 8 3 2 39 4 0 7 6 4 15 8 3 2 4 8 37 4 8 4 8 3 40

Sample Output

Problem 1: 20Problem 2: 19Problem 3: 36

Source2008 ACM-ICPC Pacific Northwest Region

Here is a map of N * N.

From the upper left corner to the lower right corner, the minimum cost of the trip. (Number is the cost)

Because not the shortest path, but the minimum cost.

Priority queue can be used, with a low priority. With BFS, a flag number is used to record the cost of any point.

The value of the flag array is constantly updated each time. Because of the priority queue, the highest priority (less cost) is always displayed)

Code on

# Include
 
  
# Include
  
   
# Include
   
    
# Include using namespace std; int n; int map [130] [130]; int flag [130] [130]; // record the cost of the specified point. Int dir [4] [2] = {0, 1}, {0,-1}, {}, {-}; # define inf 0x6fffffstruct node {int x, y; int cost; friend bool operator <(node a, node B) {return. cost> B. cost; // priority queue, which defines the priority and takes precedence if the cost is small .} }; Bool check (int x, int y) {if (x> = n | y> = n | x <0 | y <0) return 0; return 1;} int bfs (int x, int y) {int I; node st, ed; priority_queue
    
     
Q; // priority queue st. x = x; st. y = y; st. cost = map [0] [0]; memset (flag,-1, sizeof (flag); q. push (st); while (! Q. empty () {st = q. top (); // The minimum cost is incurred each time. Q. pop (); for (I = 0; I <4; I ++) {ed. x = st. x + dir [I] [0]; ed. y = st. y + dir [I] [1]; if (! Check (ed. x, ed. y) // It is enough to exclude cross-border access. If you do not want to exclude access, you can go back and traverse the entire map. Continue; ed. cost = st. cost + map [ed. x] [ed. y]; if (ed. cost