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