数据结构OJ作业——队列

POJ 3984 ：http://poj.org/problem?id=3984
迷宫，输出最短路径，bfs

#include 
#include 
#include 
#include  

using namespace std;
int maze[5][5];
pair<int, int> path[5][5];
queueint,int> > q;
int dx[]={1,-1,0,0};  
int dy[]={0,0,1,-1};  

void bfs(int x,int y)
{
    q.push(make_pair(x,y));
    while (!q.empty()) {
        pair<int, int> p = q.front(); q.pop() ;
        x = p.first; y = p.second;
        for (int i = 0; i < 4; i ++) {
            int xx = x + dx[i];
            int yy = y + dy[i];
            if (xx >= 0 && xx <= 4 && yy >= 0 && yy <= 4 && !maze[xx][yy]) {
                maze[xx][yy] = 1;
                path[xx][yy] = make_pair(x,y);
                if (xx == 0 && yy == 0) {
                    return;
                }
                q.push(make_pair(xx,yy));
            }
        }
    }
}

int main()
{
    memset(path,-1,sizeof(path));
    for (int i = 0; i < 5; i ++) {
        for (int j = 0; j < 5; j ++) {
            scanf("%d",&maze[i][j]);
        }
    }
    bfs(4,4);
    int x = 0, y = 0;
    while (x != 4 || y != 4) {
        printf("(%d, %d)\n",x,y);
        int xx = x;
        x = path[x][y].first;
        y = path[xx][y].second;

    }
    printf("(%d, %d)\n",4,4);
    return 0;
}

POJ 3278：http://poj.org/problem?id=3278
bfs即可

#include 
#include 
#include 
#include 
#include 
using namespace std;
const int MAX = 100005;
int n,k;
bool visit[MAX];
int step[MAX];
int mov[] = {1, -1};

int bfs(int x)
{

    if (n >= k) {
        return n - k;
    }
    queue<int> q;
    q.push(x);
    visit[x] = 1;
    while (!q.empty()) {
        x = q.front(); q.pop();
        //printf("%d ",x);
        for (int i = 0; i < 2; i ++) {
            int xx = x + mov[i];
            if (xx == k) {
                return step[x] + 1;
            }
            if (xx >= 0 && xx <= 100000 && !visit[xx]) {
                q.push(xx);
                visit[xx] = 1;
                step[xx] = step[x] + 1;
            }
        }
        int xx = x * 2;
        if (xx == k) {
            return step[x] + 1;
        }
        if (xx <= 100000 && !visit[xx]) {
            q.push(xx);
            visit[xx] = 1;
            step[xx] = step[x] + 1;
        }
    }

}
int main()
{
    while (~scanf("%d%d",&n,&k)) {
        memset(visit,0,sizeof(visit));
        memset(step,0,sizeof(step));
        printf("%d\n",bfs(n));
    }
}