bfs和优先队列求数据三角形最大值

此题用深搜很快就解决，我用宽度搜索和优先队列仅仅是为了练习他们的用法；深搜法在注释内；

 1 #include<iostream>
 #include<cstring>
 #include<queue>
 using namespace std;
 const int N=;
 int map[N][N];
 int vis[N][N];
 int n;
 struct Node
 {
 int x,y,value;
 friend bool operator<(Node a,Node b)
 {return a.value<b.value;
 }

 };
 /*
 int dfs(int i,int j)
 {
 if(i==n)return map[i][j];
 int num1=map[i][j]+dfs(i+1,j);
 int num2=map[i][j]+dfs(i+1,j+1);
 return num1>num2?num1:num2;
 }
 */
 int dfs(int x,int y)
 {
 priority_queue<Node>Q;
 queue<Node>q;
 Node a;
 Node b;
 a.x=x;
 a.y=y;
 a.value=map[x][y];
 q.push(a) ;
 Q.push(a);

 while(!Q.empty())
 {
 a=q.front();
 q.pop();
 if(a.x==n)return Q.top().value;
 for(int i=;i<=;i++)
 {
 b.x=a.x+;
 b.y=a.y+i;
 b.value=a.value+map[b.x][b.y];
 if(vis[b.x][b.y]<b.value)
 {
 vis[b.x][b.y]=b.value;
 q.push(b);
 Q.push(b);
 }
 }
 }
 return ;
 }
 int main()
 {

 while(cin>>n)
 {
 for(int i=;i<=n;i++)
 for(int j=;j<=i;j++)
 {
 cin>>map[i][j];
 vis[i][j]=map[i][j];
 }
 cout<<endl<<dfs(,)<<endl;
 }
 return ;
 }