76 lines
1.8 KiB
C++
76 lines
1.8 KiB
C++
#include<bits/stdc++.h>
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using namespace std;
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const int N = 10;
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string ar[N]; //由啥
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string br[N]; //变成啥
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int n; //规则个数
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string a, B; //原串，目标串
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//结构体
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struct node {
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string str;
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int step;
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};
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//队列
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queue<node> q;
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//桶,利用set去重，检查
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set<string> st;
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//广度优先搜索
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void bfs() {
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//标识原串已经使用过
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st.insert(a);
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//入队列
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q.push({a, 0});
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//广度优先
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while (!q.empty()) {
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auto p = q.front();
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q.pop();
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//如果找到
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if (p.str == b) {
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printf("%d\n", p.step);
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return;
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}
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//大于10步还没有找到
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if (p.step > 10) {
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printf("NO ANSWER!\n");
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return;
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}
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//尝试每一种变换方式
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for (int i = 0; i < n; i++) {
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//变换位置
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for (int j = 0; j < p.str.size(); j++) {
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//发现子串ar[i]
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if (p.str.compare(j, ar[i].size(), ar[i]) == 0) {
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//拷贝出来新的,因为p.str后面还在循环，不能破坏
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string s = p.str;
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//替换,replace:从哪个下标位置开始，一共多长，替换成啥
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s.replace(j, ar[i].size(), br[i]);
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//没有出现过
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if (!st.count(s)) {
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st.insert(s);
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q.push({s, p.step + 1});
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}
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}
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}
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}
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}
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//这句话很重要噢~
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printf("NO ANSWER!\n");//十步以内也无法变成b
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}
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int main() {
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//读入原串，目标串
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cin >> a >> b;
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//读入规则，按 ctrl+d结束
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while (cin >> ar[n] >> br[n]) n++;
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//广度优先搜索
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bfs();
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return 0;
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} |