1143 Lowest Common Ancestor

题意： 给出一棵二叉搜索树的前序遍历，问结点a和b的共同最低祖先是谁

#include<iostream>
#include<map>
using namespace std;
int pre[10003];
int t=0;
void find(int a,int b,int e) {t=pre[0];for(int i=0; i<e; ++i)if(pre[i]>=a&&pre[i]<=b||pre[i]<=a&&pre[i]>=b) {t=pre[i];break;}
}
int main() {int n,m;cin>>n>>m;map<int,int>num;for(int i=0; i<m; ++i) {scanf("%d",pre+i);num[pre[i]]=i+1;}for(int i=0; i<n; ++i) {int a,b;cin>>a>>b;if(!num[a]&&!num[b])printf("ERROR: %d and %d are not found.\n",a,b);else if(!num[a])printf("ERROR: %d is not found.\n",a);else if(!num[b])printf("ERROR: %d is not found.\n",b);else {t=a;find(a,b,m-1);if(t==a)printf("%d is an ancestor of %d.\n",a,b);else if(t==b)printf("%d is an ancestor of %d.\n",b,a);else printf("LCA of %d and %d is %d.\n",a,b,t);}}return 0;
}

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