HDU 4771 Stealing Harry Potter's Precious【BFS+DFS】

题目链接

从起点去偷所有珠宝，求最小步数，不考虑离开。

将贼起点也当做珠宝，先bfs求两两珠宝间距离，再dfs找最小的珠宝距离和，杭电discuss上的数据有误，当珠宝在同一地方时认为不可偷，然后杭电数据没有这种情况，所以网上好多的都这样混过去了

4 4

#@##

..#.

#.##

....

4

2 1

2 1

2 1

2 1

输出2才是王道

#include <stdio.h>
#include <string.h>
#include <queue>
using namespace std;
int m,n;
char map[105][105];
int visit[105][105];
int dir[][2] = { {-1,0}, {0,1}, {1,0}, {0,-1}};
int net[6];       //dfs的标记数组
int min_sum;
int jnum;        //包起点的总珠宝数
int jcount;      //珠宝数
int dist[6][6];
struct node{
int x;
int y;
int number;     //序号，其中贼起点为0
int step;       //求路径长度时的步数
}jerry[6];
bool inmap(int x,int y){
if(x >= 1 && x <= n)
if( y >=1 && y <= m)
return true;
return false;
}
void dfs(int index,int sum,int count){
if(count == jcount){
if(sum < min_sum)
min_sum = sum;
return;
}
for(int i=1;i<jnum;i++){
if(!net[i]){
net[i] = 1;
dfs(i,sum+dist[index][i],count+1);
net[i] = 0;
}
}
return;
}

int bfs(struct node s,struct node e){
queue<struct node> q;
int tx,ty;
struct node temp,cur;
while(!q.empty())
q.pop();
q.push(s);
visit[s.x][s.y] = 1;
if(s.x == e.x && s.y== e.y)return 0;
while(!q.empty()){
cur = q.front();
q.pop();
for(int i=0;i<4;i++){
tx = cur.x + dir[i][0];
ty = cur.y + dir[i][1];
temp.x = tx;
temp.y = ty;
temp.step = cur.step + 1;
if( !visit[tx][ty] && inmap(tx,ty) && map[tx][ty] != '#' ){
visit[tx][ty] = 1;
if(tx == e.x && ty == e.y){
return temp.step;
}
q.push(temp);
}
}
}
return -1;
}
int main()
{
int i,j,k,tx,ty,flag;
#ifndef ONLINE_JUDGE
freopen("in.txt","r",stdin);
#endif
while(scanf("%d%d",&n,&m)!=EOF,m+n){
getchar();
for(i=1;i<=n;i++){
for(j=1;j<=m;j++){
scanf("%c",&map[i][j]);
if(map[i][j] =='@'){
jerry[0].x = i;
jerry[0].y = j;
jerry[0].number = 0;
}
}
getchar();
}
scanf("%d",&jcount);
for(i=1;i<=jcount;i++){
scanf("%d%d",&jerry[i].x,&jerry[i].y);
jerry[i].number = i;
}
jnum = jcount+1;
flag = 0;
for(i=0;i<jnum;i++){
for(j=i+1;j<jnum;j++){
memset(visit,0,sizeof(visit));
dist[i][j] = dist[j][i] = bfs(jerry[i],jerry[j]);
if(dist[i][j] == -1){
flag = 1;
break;
}
}
}
if(flag == 1){
printf("-1\n");
}
else{
min_sum = 1<<20;
memset(net,0,sizeof(net));
net[0] = 1;
dfs(0,0,0);
printf("%d\n",min_sum);
}
}
return 0;
}