hdoj 4198 Quick out of the Harbour

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类型：bfs + 优先队列

题目：http://acm.hdu.edu.cn/showproblem.php?pid=4198

来源：BAPC 2011

思路：扩展完当前节点后，将"路径"小的节点出队，进行扩展。

！！！S点可能在边上

// hdoj 4198 Quick out of the Harbour// wa ac 125MS 764K#include <iostream>#include <sstream>#include <string>#include <queue>#include <stack>#include <map>#include <algorithm>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>using namespace std;#define FOR(i,a,b) for(i = (a); i < (b); ++i)#define FORE(i,a,b) for(i = (a); i <= (b); ++i)#define FORD(i,a,b) for(i = (a); i > (b); --i)#define FORDE(i,a,b) for(i = (a); i >= (b); --i)#define CLR(a,b) memset(a,b,sizeof(a))#define PB(x) push_back(x)const int MAXN = 510;const int MAXM = 0;const int hash_size = 25000002;const int INF = 0x7f7f7f7f;bool vis[MAXN][MAXN];int test, h, w, d, sx, sy;int dirx[4] = {-1, 0, 1, 0}, diry[4] = {0, 1, 0, -1};char str[MAXN][MAXN];struct node {    int x, y, step;};bool operator > (const node &a, const node &b) {    return a.step > b.step;}bool operator < (const node &a, const node &b) {    return a.step < b.step;}priority_queue<node, vector<node>, greater<node> > q;void init() {    int i, j;    scanf("%d %d %d", &h, &w, &d);    CLR(vis, false);    while(!q.empty())        q.pop();    FORE(i, 1, h) {        scanf("%s", str[i] + 1);        FORE(j, 1, w)            if(str[i][j] == 'S')                sx = i, sy = j;    }}int bfs() {    int i;    node a, b;    a.x = sx, a.y = sy, a.step = 1;    q.push(a);    //!!!    if(a.x == 1 || a.x == h || a.y == 1 || a.y == w)        return a.step;    while(!q.empty()) {        a = q.top();        q.pop();        FORE(i, 0, 3) {            int tmp_x = a.x + dirx[i], tmp_y = a.y + diry[i];            if(tmp_x < 1 || tmp_x > h || tmp_y < 1 || tmp_y > w || vis[tmp_x][tmp_y] || str[tmp_x][tmp_y] == '#')                continue;            vis[tmp_x][tmp_y] = true;            b.x = tmp_x, b.y = tmp_y;            if(str[tmp_x][tmp_y] == '.')                b.step = a.step + 1;            else                b.step = a.step + 1 + d;            if(b.x == 1 || b.x == h || b.y == 1 || b.y == w)                return b.step;            q.push(b);        }    }}int main() {    scanf("%d", &test);    while(test--) {        init();        printf("%d\n", bfs());    }    return 0;}