SJTU OJ 1056 二哥吃糖

原题链接

这道题查找第q大的糖果数用平衡树就可以（平衡度用结点个数而不是高度，返回第q大更快）。其他要注意的就是标记好几号盒子并到了几号盒子里。初始化第i个糖果在第i个盒子里。
下面是代码：

#include <iostream>#include <cstdio>using namespace std;int m, n;int box[500005];//每个盒子多少个糖;int sugar[500005];//每个糖属于几号盒子;int movebox[500005] = {0};//每个盒子合并到哪个盒子;int boxnum;template<class T>class BinarySearchTree{private:    struct BinaryNode{        T data;        BinaryNode * left;        BinaryNode * right;        int height;        BinaryNode(const T& otherdata, BinaryNode * otherl, BinaryNode * otherr):data(otherdata), left(otherl), right(otherr), height(1){}    };public:    BinarySearchTree(BinaryNode * t = NULL){root = t;}    ~BinarySearchTree() {makeEmpty(root);}    bool find(const T& x)const{        return find(x, root);    }    void insert(const T& x){        insert(x, root);    }    void remove(const T& x){        remove(x, root);    }    T& findkth(int i){        return findkth(i, root);    }private:    BinaryNode * root;    void insert(const T& x, BinaryNode * &t){        if (t==NULL) t = new BinaryNode(x, NULL, NULL);        else if (x>t->data) {            insert(x, t->left);            if (h(t->left)-h(t->right) == 2){                if (x > t->left->data){                    LL(t);                }                else LR(t);            }            t->height = h(t->left) + h(t->right) + 1;        }        else {            insert(x, t->right);            if (h(t->right)-h(t->left) == 2){                if (x <= t->right->data){                    RR(t);                }                else RL(t);            }            t->height = h(t->left) + h(t->right) + 1;        }    }    void remove(const T& x, BinaryNode * &t){        if (t == NULL) return;        if (x>t->data) {            remove(x, t->left);            if (h(t->right) - h(t->left) == 2){                BinaryNode *r =  t->right;                if (h(r->left) > h(r->right))                    RL(t);                else                    RR(t);            }            t->height = h(t->left) + h(t->right) + 1;        }        else if (x<t->data) {            remove(x, t->right);            if (h(t->left) - h(t->right) == 2){                BinaryNode *r =  t->left;                if (h(r->right) > h(r->left))                    LR(t);                else                    LL(t);            }            t->height = h(t->left) + h(t->right) + 1;        }        else if (t->left != NULL && t->right != NULL){            if (h(t->left) <= h(t->right)){                BinaryNode * tmp = t->right;                while(tmp->left != NULL) tmp = tmp->left;                t->data = tmp->data;                remove(t->data, t->right);                t->height = h(t->left) + h(t->right) + 1;            }            else{                BinaryNode * tmp = t->left;                while (tmp->right != NULL) tmp = tmp->right;                t->data = tmp->data;                remove(t->data, t->left);                t->height = h(t->left) + h(t->right) + 1;            }        }        else{            BinaryNode * old = t;            t = (t->left != NULL) ? t->left : t->right;            delete old;        }    }    bool find(const T& x, BinaryNode * t)const{        if (t == NULL) return false;        if (x>t->data) return find(x, t->left);        if (x<t->data) return find(x, t->right);        return true;    }    void makeEmpty(BinaryNode * &t){        if (t == NULL) return;        BinaryNode * tmp = t;        makeEmpty(t->left);        makeEmpty(t->right);        delete tmp;        t = NULL;    }    T& findkth(int i, BinaryNode *&t){        int rs = h(t->left);        if (rs == i-1){            return t->data;        }        if (rs >= i) return findkth(i, t->left);        else return findkth(i-rs-1, t->right);    }    int h(BinaryNode * t){        return t==NULL ? 0 : t->height;    }    void LL(BinaryNode *&t){        BinaryNode * t1 = t->left;        t->left = t1->right;        t1->right = t;        t->height = h(t->left) + h(t->right) + 1;        t1->height = h(t1->left) + h(t)+1;        t = t1;    }    void RR(BinaryNode *&t){        BinaryNode * t1 = t->right;        t->right = t1->left;        t1->left = t;        t->height = h(t->left) + h(t->right) + 1;        t1->height = h(t1->right) + h(t)+1;        t = t1;    }    void LR(BinaryNode *&t){        RR(t->left);        LL(t);    }    void RL(BinaryNode *&t){        LL(t->right);        RR(t);    }};int main(){    scanf("%d%d", &n, &m);    BinarySearchTree<int> t;    for (int i=1; i<=n; i++){        box[i] = 1;        t.insert(1);        sugar[i] = i;    }    boxnum = n;    char query;    int x, y;    while (m--){        query = getchar();        query = getchar();        switch(query){        case 'C':            scanf("%d%d", &x, &y);            while (movebox[sugar[x]] != 0){//找到x糖果现在在几号盒子;                sugar[x] = movebox[sugar[x]];            }            while (movebox[sugar[y]] != 0){//找到y糖果现在在几号盒子;                sugar[y] = movebox[sugar[y]];            }            if (sugar[y] != sugar[x] && box[sugar[x]] != 0 && box[sugar[y]] != 0){                t.remove(box[sugar[x]]);                t.remove(box[sugar[y]]);                box[sugar[x]] += box[sugar[y]];                t.insert(box[sugar[x]]);                box[sugar[y]] = 0;                movebox[sugar[y]] = sugar[x];//y的盒子移动到x的盒子;                boxnum--;            }            break;        case 'D':            scanf("%d", &x);            while (movebox[sugar[x]] != 0){//同上;                sugar[x] = movebox[sugar[x]];            }            if (box[sugar[x]] != 0){                t.remove(box[sugar[x]]);                box[sugar[x]] = 0;                boxnum--;            }            break;        case 'Q':            scanf("%d", &x);            if (boxnum < x) printf("%d\n", 0);            else{                printf("%d\n", t.findkth(x));            }            break;        default:            cout << "Wrong!\n";            break;        }    }    return 0;}

欢迎指正！