poj 2182 Lost Cows

来源：互联网发布：腾讯云怎么解析cn域名编辑：程序博客网时间：2024/06/10 21:32

原题链接：http://poj.org/problem?id=2182
题意：n个牛编号为1-n 现在编号顺序已经打乱，给出a[i] ,a[i] 代表i位置前面有几个小于它的编号，求编号顺序。倒着推，对于最后一个a[i] , 最后位置编号肯定是 a[i]+1,然后在1-n个编号中删掉当前编号，继续往前推。。即求第 a[i]+1小数，初始容器中有n个数（1-n），每求出来一个就删掉。
好像可以用线段树做，不过我用Treap求的。
具体做法看下面吧：

#include<stdio.h>#include<stdlib.h>#include<string.h>#define node_size(T) (((T)!=NULL) ? ((T)->size) : 0)#define _size(T) (node_size((T)->left) + node_size((T)->right) + 1)typedef struct _treap{    int val, size, fix;    struct _treap *left, *right;}treap, *Treap;treap node[8010];int sz, ans[8010];int _random(){    static int x = 1364684679;    x += (x << 2) + 1;    return x;}void rotate_left(Treap *T){    Treap k = (*T)->right;    (*T)->right = k->left;    k->left = *T;    (*T)->size = _size(*T);    k->size = _size(k);    *T = k;}void rotate_right(Treap *T){    Treap k = (*T)->left;    (*T)->left = k->right;    k->right = *T;    (*T)->size = _size(*T);    k->size = _size(k);    *T = k;}void insert(Treap *T, int val, int fix){    if (*T == NULL){        *T = &node[sz++];        memset(*T, 0, sizeof(treap));        (*T)->size = 1, (*T)->val = val, (*T)->fix = fix;    } else if (val < (*T)->val){        (*T)->size++;        insert(&((*T)->left), val, fix);        if ((*T)->left->fix < (*T)->fix)            rotate_right(T);    } else if (val >(*T)->val){        (*T)->size++;        insert(&((*T)->right), val, fix);        if ((*T)->right->fix < (*T)->fix)            rotate_left(T);    }}void _remove(Treap *T, int val){    if ((*T)->val == val){          if ((*T)->left == NULL || (*T)->right == NULL){            *T = (*T)->left != NULL ? (*T)->left : (*T)->right;        } else if ((*T)->left->fix < (*T)->right->fix){            rotate_right(T);            (*T)->size--;            _remove(&((*T)->right), val);        } else {            rotate_left(T);            (*T)->size--;            _remove(&((*T)->left), val);        }    } else if (val < (*T)->val){        (*T)->size--;        _remove(&((*T)->left), val);    } else {        (*T)->size--;        _remove(&((*T)->right), val);    }}Treap find_kth(Treap T, int k){    int x = node_size(T->left);    if (k < x + 1) return find_kth(T->left, k);    else if (k > x + 1) return find_kth(T->right, k - (x + 1));    else return T;}int main(){#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    int n, i;    Treap root = NULL;    while (~scanf("%d", &n)){        sz = 0, root = NULL;        for (i = 1; i <= n; i++) insert(&root, i, _random());        for (i = 0; i < n - 1; i++) scanf("%d", &ans[i]);        for (i = n - 2; i >= 0; i--){            ans[i] = find_kth(root, ans[i] + 1)->val;            _remove(&root, ans[i]);        }        printf("%d\n", root->val);        for (i = 0; i < n - 1; i++) printf("%d\n", ans[i]);    }    return 0;}

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