'commit'

TangDou/AcWing/BFS/845_unordered_map.cpp

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+using namespace std;
+int dx[] = {-1, 0, 1, 0};
+int dy[] = {0, 1, 0, -1};
+string ed = "12345678x";
+
+unordered_map<string, int> d;
+
+int bfs(string s) {
+    queue<string> q;
+    q.push(s);
+    d[s] = 0;
+
+    while (q.size()) {
+        auto u = q.front();
+        q.pop();
+        
+        if (u == ed) return d[u];
+        int k = u.find('x');
+        int x = k / 3, y = k % 3; // 一维变二维,准备变更，判断变更后会不会出界
+
+        for (int i = 0; i < 4; i++) {
+            int tx = x + dx[i], ty = y + dy[i];
+            if (tx < 0 || tx > 2 || ty < 0 || ty > 2) continue;
+
+            string c = u;               // 抄出来c
+            swap(c[k], c[tx * 3 + ty]); // 在c上进行变更，二维变一维
+            if (!d.count(c)) {          // 这个状态没到达过
+                d[c] = d[u] + 1;        // 记录是第几步到达
+                q.push(c);
+            }
+        }
+    }
+    return -1;
+}
+
+int main() {
+    string s;
+    char c;
+    for (int i = 1; i <= 9; i++) { // 输入的是9个字符，每两个中间有空格
+        cin >> c;
+        s += c;
+    }
+    cout << bfs(s) << endl;
+    return 0;
+}