NYOJ483噩梦(优先队列 + 无标记)

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题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=483

本题重点是访问完一次4之后要置成1或者0，防止多次重置。

因为这个我错了好多次。

代码：

#include <cstdio>#include <queue>#include <cstring>#include <vector>#include <algorithm>using namespace std;typedef struct {    int x,y;    int time;    int step;}node;node st;int n,m;int a[10][10];int enx,eny;int dx[] = {-1,0,1,0};int dy[] = {0,1,0,-1};struct cmp{    bool operator()(node i,node j)    {        return i.step > j.step;    }};int bfs(){    priority_queue<node,vector<node>,cmp> q;    node t,head;    st.time = 6;    st.step = 0;    q.push(st);    while(!q.empty())    {        head = q.top();        q.pop();       // printf("%d %d %d %d\n",head.x,head.y,head.time,head.step);        if(head.time == 1)            continue;        if(head.x == enx && head.y == eny && head.time > 0)        {            return head.step;        }        for(int i = 0;i < 4;++i)        {            t.x = head.x + dx[i];            t.y = head.y + dy[i];            t.step = head.step + 1;            t.time = head.time - 1;            if(t.x >= 1 && t.x <= n && t.y >= 1 && t.y <= m && a[t.x][t.y])            {                if(a[t.x][t.y] == 4 && t.time > 0)                {                     a[t.x][t.y] = 1;                     t.time = 6;                }                else if(a[t.x][t.y] == 3 && t.time > 0)                {                    return t.step;                }                q.push(t);            }        }    }    return -1;}int main(){    int t;    scanf("%d",&t);    while(t--)    {       // memset(v,0,sizeof(v));        scanf("%d%d",&n,&m);        for(int i = 1;i <= n;++i)        {            for(int j = 1;j <= m;++j)            {                scanf("%d",&a[i][j]);                if(a[i][j] == 2)                {                    st.x = i;                    st.y = j;                }                else if(a[i][j] == 3)                {                    enx = i;                    eny = j;                }            }        }        printf("%d\n",bfs());       // printf("%d %d %d %d\n",stx,sty,enx,eny);    }}

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