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C++专题课程/广度优先搜索/BFS解救小哈.txt

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+https://www.cnblogs.com/captainad/p/11053238.html

C++专题课程/广度优先搜索/Bfs.cpp

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+#include <bits/stdc++.h>
+
+using namespace std;
+
+int a[11][11] =
+        {
+                {1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
+                {1, 0, 0, 1, 0, 0, 0, 1, 0, 1},
+                {1, 0, 0, 1, 0, 0, 0, 1, 0, 1},
+                {1, 0, 0, 0, 0, 1, 1, 0, 0, 1},
+                {1, 0, 1, 1, 1, 0, 0, 0, 0, 1},
+                {1, 0, 0, 0, 1, 0, 0, 0, 0, 1},
+                {1, 0, 1, 0, 0, 0, 1, 0, 0, 1},
+                {1, 0, 1, 1, 1, 0, 1, 1, 0, 1},
+                {1, 1, 0, 0, 0, 0, 0, 0, 0, 1},
+                {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
+        };
+int dir[4][2] = {{-1, 0},
+                 {0,  1},
+                 {1,  0},
+                 {0,  -1}};
+int vis[11][11];//用来标记有没有走过（有没有在队列中)
+int b[11][11];//用来记录bfs的过程
+struct Node {
+    int x, y;
+};
+queue<Node> q;
+
+int main() {
+    memset(b, 0, sizeof(b));
+    memset(vis, 0, sizeof(vis));
+    while (!q.empty()) q.pop();//初始化队列
+
+    Node start;
+    start.x = 1;
+    start.y = 1;
+    vis[1][1] = 1;
+    b[1][1] = 1;
+    q.push(start);//把起点放进队列
+    bool f = 0;
+    while (!q.empty()) {
+        Node temp;
+        temp = q.front();//取出队头元素
+        q.pop();
+        int x = temp.x;
+        int y = temp.y;
+        if (x == 8 && y == 8)//若走到了
+        {
+            f = 1;
+            Node road[111];//用来记录路径
+            //for(int i=1;i<=8;i++)//可以通过输出b数组来观察bfs的实现过程
+            //{
+            //    for(int j=1;j<=8;j++)
+            //    {
+            //        printf("%5d",b[i][j]);
+            //    }
+            //    cout<<endl;
+            //}
+            //cout<<b[8][8]<<endl;
+            int k = 1;
+            while (!(x == 1 && y == 1))//通过b数组来找到之前是哪一个点走到x，y的
+            {
+                road[k].x = x;
+                road[k++].y = y;
+                for (int i = 0; i < 4; i++) {
+                    int xx = x + dir[i][0];
+                    int yy = y + dir[i][1];
+                    if (xx < 1 || yy < 1 || xx > 8 || yy > 8) continue;//超出范围的不要
+                    if (b[xx][yy] == b[x][y] - 1) {
+                        x = xx;//倒退回去
+                        y = yy;
+                        break;//一定要跳出，要把更新的x，y放到road里
+                    }
+                }
+            }
+            road[k].x = 1;//别忘了把起点放进去
+            road[k].y = 1;
+            for (int i = k; i >= 1; i--)//输出路径
+            {
+                cout << road[i].x << " " << road[i].y << endl;
+            }
+        }
+        if (f == 1) //找到路了就不用再跑大循环了
+            break;
+
+        for (int i = 0; i < 4; i++)//遍历四个方向
+        {
+            int xx = x + dir[i][0];
+            int yy = y + dir[i][1];
+            if (a[xx][yy] == 0 && vis[xx][yy] == 0) {
+                vis[xx][yy] = 1;
+                Node New;
+                New.x = xx;
+                New.y = yy;
+                b[xx][yy] = b[x][y] + 1;//用来标记走到（xx，yy）是第几步
+                q.push(New);//放进队列
+            }
+        }
+    }
+    return 0;
+}