c++题解，代码没有注释，可从上网查询，输出必须符合样例，本题有8个测试点，请得满分。
T-2 Breaking Through
分数 35
作者 陈越
单位 浙江大学
In a war
game, you are given a map consists
of n×n square blocks
. Starting from your current block, your task is to conquer a destination block as fast as you can
. The difficulties are not only that some
of the blocks are occupied by enemies, but also that
they are shooting in some directions
. When one is shooting in some direction,
the whole row/column in that direction will be covered by fire, unless
there is ano
ther enemy blocking
the way
. You must make sure that you are not shot on
the way to your destination
.
However, it is very much likely, at
the very beginning, that this task is impossible
. So you must follow
the following instructions:
Step 1: find
the shortest path from
the starting block to
the destination, avoiding all
the enemy blocks
. The path length is
the number
of blocks on
the way, not including
the starting block
.
If this path is not unique, select
the smallest index sequence – that is, all
the blocks are indexed from 1 to n
2
, starting from
the upper-left corner, and row by row till
the lower-right corner
. An index sequence is an ordered sequence
of the block indices from
the starting block to
the destination
. One sequence { s,u
1
,⋯,u
k
,d } is said to be smaller than { s,v
1
,⋯,v
k
,d }, if
there exists 1≤p≤k such that u
i
=v
i
for i<p and u
p
<v
p
.
Step 2: if some
of the blocks along
the selected shortest path is covered by fire, conquer and clear
the nearest reachable enemy block that are firing at
the path (in case that such a block is not unique,
take the one with
the smallest index)
. Then
take that block as
the starting position, goto step 1
. Keep in mind that you must always make sure that you are not shot on
the way
.
If step 2 is impossible,
then
the game is over
. O
therwise, keep going until you finally conquer
the destination
.
Input Specification:
Each input file contains one test case
. For each case,
the first line contains a positive integer n (3≤n≤100), which is
the size
of the map
. Then n lines follow, each gives n
numbers. Each number describes
the status
of the corresponding block:
0 means
the block is clear;
1, 2, 3, or 4 means
the block is occupied by an enemy, who will shoot toward up, down, left, and right, respectively;
5 means
the block is your starting position;
6 means
the block is your destination
.
All
the numbers in a line are separated by a space
.
Note:
You can never cross any
of the boundaries
of the map
.
When an enemy is shooting from block A in direction B, every block starting from A in direction B will be covered by fire, untill
the boundary is reached, or ano
ther enemy block is encountered
.
The enemies will never kill each o
ther
. Only you will get killed if you step into a block that is covered by fire
.
It is guaranteed that
there is no more than n enemy blocks, and your starting position is not on fire
.
Output Specification:
Print in a line
the path length for you to reach
the last block from your starting position, and
the block number
. The two
numbers must be separated by 1 space
.
In
the next line, print Win if
the destination is reached, or Lose if not
.
Sample Input 1:
6
6 2 0 0 0 0
0 0 0 0 0 0
0 4 0 0 0 0
0 0 0 0 1 0
0 0 0 3 5 0
4 0 0 0 0 0
Sample Output 1:
10 1
Win
Hint:
The movements are shown by
the following figures 14
.
Figure 1 shows how
the blocks are numbered
.
Figure 2 shows
the initial status
of the map, where
the player’s position is green, enemy blocks are black, and red blocks are covered by fire
.
At
the very beginning
the shortest path was 29->30->24->18->12->11->10->9->8->7->1, but
the path was covered by fire shooting from blocks 23, 14 and 2
. Since
the enemy block 23 is
the nearest reachable one, it was cleared with path length 1
.
Now starting from block 23,
the shortest path was 23->17->11->10->9->8->7->1, but
the path was covered by fire shooting from blocks 14 and 2
. Since
the enemy block 14 is covered by fire from block 2,
taking block 2 now is
the only option
. So next, block 2 is cleared with path length 8 (crossing
the destination)
.
Finally we can get to
the destination from block 2 to 1
.
Sample Input 2:
4
5 0 2 0
0 0 0 0
0 1 0 0
4 0 6 3
Sample Output 2:
6 3
Lose
Hint:
The movements are shown by
the following figures 5~8
.
Figure 5 shows how
the blocks are numbered
.
Figure 6 shows
the initial status
of the map
.
At
the very beginning
the shortest path was 1->2->6->7->11->15, but
the path was covered by fire shooting from blocks 3, 10, 13 and 16
. Since
the enemy block 10 is
the nearest reachable one, it was cleared with path length 3
.
Now starting from block 10,
the shortest path was 10->11->15, but
the path was covered by fire shooting from blocks 3, 13 and 16
. Since
the enemy blocks 13 and 16 are covered by fire from each o
ther,
taking block 3 now is
the only option
. So next, block 3 is cleared with path length 3
.
Now it is clear that
there is no way to conquer
the destination, since block 15 is fired by 13 and 16, yet we cannot clear any
of them without getting fired
. Hence
the last block we can reach is 3
.
steps2
.png
代码长度限制
16 KB
时间限制
400 ms
内存限制
64 MB
栈限制
8192 KB
本文介绍了一种基于数组的游戏算法，两人轮流从数组两端取数，目标是使所取数值之和最大化。通过记忆化搜索实现最优解策略，确保先手玩家得分优势。
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