上周的训练题,脑袋糊了,D题交到C题,WA了两次,只能补题了IDA * 没看完,以后再补!
贴下神牛牪犇AC代码
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;
int pos[][2] = {3,3,0,0,0,1,0,2,
0,3,1,0,1,1,1,2,
1,3,2,0,2,1,2,2,
2,3,3,0,3,1,3,2};
int dx[] = {0,1,-1,0};
int dy[] = {1,0,0,-1};
char dir[] = {'R','D','U','L'};
int en[16] = {1,2,3,4,
5,6,7,8,
9,10,11,12,
13,14,15,0};
char path[100];
int puz[16];
int hstar()
{
int h = 0;
for(int i = 0; i < 16; ++i){
int x = puz[i];
if(x == 0) continue;
h += abs(i / 4 - pos[x][0]) + abs(i % 4- pos[x][1]);
}
return h;
}
bool dfs(int p,int pre,int d, int maxd)
{
if(d + hstar() > maxd) return false;
if(d == maxd)
return memcmp(puz,en,sizeof(en)) == 0;
int x = p / 4, y = p % 4;
for(int j = 0; j < 4; ++j){
if(pre + j == 3) continue;
int nx = x + dx[j], ny = y + dy[j];
int nz = 4 * nx + ny;
if(nx >= 0 && nx < 4 && ny >= 0 && ny < 4){
swap(puz[p],puz[nz]);
path[d] = dir[j];
if(dfs(nz,j,d+1,maxd)) return true;
swap(puz[p],puz[nz]);
}
}
return false;
}
bool solvable()
{
int cnt = 0;
for(int i = 0; i < 16; ++i){
if(puz[i] == 0)
cnt += 3 - i / 4;
else{
for(int j = 0; j < i; ++j)
if(puz[j] && puz[j] > puz[i])
cnt++;
}
}
return !(cnt&1);
}
int main(void)
{
//freopen("input.txt","r",stdin);
int T,p;
scanf("%d",&T);
while(T--){
for(int i = 0; i < 16; ++i){
scanf("%d",&puz[i]);
if(puz[i] == 0)
p = i;
}
if(solvable()){
int maxd = 0;
for(;!dfs(p,-1,0,maxd); ++maxd);
path[maxd] = 0,puts(path);
}
else
puts("This puzzle is not solvable.");
}
return 0;
}