2024-10-12 11:29:37 +00:00
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# algorithm_2024
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algorithm_2024
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## 错题本
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### Luogu某题
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#### 数组越界导致变量异常更改
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### [OJ4980:拯救行动](http://noi.openjudge.cn/ch0205/4980/)
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#### 未考虑无答案（特殊情况）时输出
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#### 优先对联是从大到小排序，重载运算符时需反向或者std::greater
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```cpp
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struct Status{
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Point now;
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ll step;
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bool operator<(const Status &that)const noexcept{
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return this->step > that.step;
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}
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};
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std::priority_queue<Status> q;
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2024-10-13 04:14:36 +00:00
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```
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### [P1330](https://www.luogu.com.cn/problem/P1330)
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#### BFS时注意初始化一开始的去重数组
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```cpp
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void bfs(){
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for(ll i{1};i<=n;i++){
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color_sum[1]=color_sum[2]=0;
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if(vis[i])continue;
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q.push(i);
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set_color(i, 1);
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vis[i]=true; // 注意初始化错误
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while(!q.empty()){
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2024-10-13 05:36:20 +00:00
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```
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### [P3957](https://www.luogu.com.cn/problem/P3957)
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#### 初始状态依赖已走过的部分时注意起始点状态
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```cpp
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for(ll coin{0};coin<=(points[n].posit-d);++coin){
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for(ll i{0};i<max_n;i++)dp[i]=ll_min;
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dp[0]=0; // 注意第0个点是能到达的reachable
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2024-10-11 09:02:47 +00:00
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```
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