POJ-2201 Cartesian Tree（笛卡尔树)

来源：互联网发布：d3.js百度百科编辑：程序博客网时间：2024/05/26 09:53

笛卡尔树是一棵二叉树，树的每个节点有两个值，一个为key，一个为value。光看key的话，笛卡尔树是一棵二叉搜索树，每个节点的左子树的key都比它小，右子树都比它大；光看value的话，笛卡尔树有点类似堆，根节点的value是最小（或者最大）的，每个节点的value都比它的子树要大。

#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>#include <vector>#include <stack>#include <queue> #define maxn 50005#define INF 1e9typedef long long ll;using namespace std;struct Node{    int l1, r1, pre, p, l2, r2;    int k, v;}node[maxn];int n, Stack[maxn];void Build(){    Stack[1] = 1;    int t = 1;    for(int i = 2; i <= n; i++){        while(t > 0 && node[Stack[t]].v > node[i].v)         t--;        if(t){            int d = Stack[t];            node[i].l1 = node[d].r1;            node[i].pre = node[d].p;            node[d].r1 = node[i].p;            node[i].l2 = node[d].r2;            node[d].r2 = i;            node[node[i].l2].pre = node[i].p;            Stack[++t] = i;        }        else{            node[i].l1 = node[Stack[1]].p;            node[Stack[1]].pre = node[i].p;            node[i].l2 = Stack[1];            Stack[++t] = i;        }    }}int cmp(const Node&a, const Node&b){    return a.k < b.k;}int temp(const Node&a, const Node&b){    return a.p < b.p;}int main(){//  freopen("in.txt", "r", stdin);    while(scanf("%d", &n) == 1){        for(int i = 1; i <= n; i++){            scanf("%d%d", &node[i].k, &node[i].v);            node[i].l1 = node[i].r1 = node[i].pre = 0;            node[i].p = i;        }        sort(node+1, node+1+n, cmp);        Build();         sort(node+1, node+1+n, temp);        puts("YES");        for(int i = 1; i <= n; i++){            printf("%d %d %d\n", node[i].pre, node[i].l1, node[i].r1);        }    }    return 0;}

0 0