UVa 10410 - Tree Reconstruction ( DFS, BFS, 栈 )

题意

思路

AC代码

#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
#include <stack>

using namespace std;

const int maxn = 1000 + 10;

vector<int> G[maxn];
int pos[maxn];
stack<int> s;

int main()
{
int n, x;
while( ~scanf("%d",&n) ){
for( int i = 1; i <= n; i++ ){
scanf("%d",&x);
if( G[i].size() ) G[i].clear();
pos[x] = i;
}
int root;
scanf("%d",&root);
while(!s.empty())  s.pop();
s.push(root);
for( int i = 1; i < n; i++ ){
scanf("%d",&x);
for(;;){
int t = s.top();
if(pos[t]+1 < pos[x] || t == root){
G[t].push_back(x);
s.push(x);
break;
}
else { s.pop(); }
}
}
for( int i = 1; i <= n; i++ ){
printf("%d:",i);
int len = G[i].size();
for( int j = 0; j < len; j++ )
printf(" %d",G[i][j]);
puts("");
}
}
return 0;
}