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【CodeVS 1199】【NOIP 2012】开车旅行

http://codevs.cn/problem/1199/

主要思想是倍增,对于第一个回答从后往前扫,依次插入平衡树中。

我写的splay,比较繁琐。

#include<cmath>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int N = 100003;int in() {	int k = 0, fh = 1; char c = getchar();	for(; c < ‘0‘ || c > ‘9‘; c = getchar())		if (c == ‘-‘) fh = -1;	for(; c >= ‘0‘ && c <= ‘9‘; c = getchar())		k = (k << 3) + (k << 1) + c - ‘0‘;	return k * fh;}int h[N], n, m, nxt_a[N], nxt_b[N], f[N][18], sum_a[N][18], sum_b[N][18];struct Splay {	struct node {		node *ch[2], *fa;		int id, num;		bool pl() {return fa->ch[1] == this;}		void setc(node *r, bool c) {ch[c] = r; r->fa = this;}	} *root, *null;	void init() {		null = new node;		null->id = null->num = 0;		null->ch[0] = null->ch[1] = null->fa = null;		root = null;	}	void printall(node *r) {		if (r == null) return;		printall(r->ch[0]);		printf("%d ", r->num);		printall(r->ch[1]);	}	void rotate(node *r) {		node *f = r->fa;		bool c = r->pl();		if (f != root) f->fa->setc(r, f->pl());		else root = r, r->fa = null;		f->setc(r->ch[!c], c);		r->setc(f, !c);	}	void splay(node *r) {		for(; r->fa != null; rotate(r))			if (r->fa->fa != null) rotate(r->fa->pl() == r->pl() ? r->fa : r);	}	struct data {		int del, h, id;		bool operator < (const data &A) const {			return (del == A.del ? h < A.h : del < A.del);		}	} a[5];	node *getl(int num, int to) {		node *r = root->ch[0];		if (r == null) {a[to] = (data) {0x7fffffff, 0, 0}; return r;}		while (r->ch[1] != null) r = r->ch[1];		a[to] = (data) {abs(num - r->num), r->num, r->id};		return r;	}	node *getr(int num, int to) {		node *r = root->ch[1];		if (r == null) {a[to] = (data) {0x7fffffff, 0, 0}; return r;}		while (r->ch[0] != null) r = r->ch[0];		a[to] = (data) {abs(num - r->num), r->num, r->id};		return r;	}	void mk_nxt(int &back_1, int &back_2, int id, int num) {		node *r = root;		if (r == null) {			root = new node;			root->id = id; root->num = num;			root->ch[0] = root->ch[1] = root->fa = null;			back_1 = back_2 = 0;			return;		}		bool c;		while (true) {			if (r->num > num) c = 0;			else c = 1;			if (r->ch[c] == null) {				r->ch[c] = new node;				r->ch[c]->fa = r;				r = r->ch[c];				r->id = id; r->num = num;				r->ch[0] = r->ch[1] = null;				splay(r);				node *ll = getl(num, 0), *rr = getr(num, 1);				if (ll != null) {splay(ll); getl(num, 2);} else a[2] = (data) {0x7fffffff, 0, 0};				if (rr != null) {splay(rr); getr(num, 3);} else a[3] = (data) {0x7fffffff, 0, 0};				sort(a, a + 4);				if (a[1].id != 0) {					back_1 = a[1].id; back_2 = a[0].id;				} else if (a[0].id != 0) {					back_1 = 0; back_2 = a[0].id;				} else {					back_1 = 0; back_2 = 0;				}				return;			} else r = r->ch[c];		}	}} T;void cal(int &a, int &b, int s, int x) {	a = b = 0;	for(int i = 17; i >= 0; --i)		if (f[s][i] && sum_a[s][i] + sum_b[s][i] <= x) {			a += sum_a[s][i]; b += sum_b[s][i];			x -= sum_a[s][i]; x -= sum_b[s][i];			s = f[s][i];		}	if (sum_a[s][0] <= x && nxt_a[s])		a += sum_a[s][0];}int main() {	T.init();	n = in();	for(int i = 1; i <= n; ++i) h[i] = in();	for(int i = n; i >= 1; --i)	T.mk_nxt(nxt_a[i], nxt_b[i], i, h[i]);		for(int i = 1; i <= n; ++i) {		if (nxt_a[i]) sum_a[i][0] = abs(h[nxt_a[i]] - h[i]);		if (nxt_b[nxt_a[i]]) {			sum_b[i][0] = abs(h[nxt_b[nxt_a[i]]] - h[nxt_a[i]]);			f[i][0] = nxt_b[nxt_a[i]];		}	}	for(int j = 1; j <= 17; ++j)		for(int i = 1; i <= n; ++i)			if (f[f[i][j - 1]][j - 1]) {				f[i][j] = f[f[i][j - 1]][j - 1];				sum_a[i][j] = sum_a[i][j - 1] + sum_a[f[i][j - 1]][j - 1];				sum_b[i][j] = sum_b[i][j - 1] + sum_b[f[i][j - 1]][j - 1];			}		int a, b, s, x, ans = 0; double ans_num = -1.0, now;	x = in();	for(int i = 1; i <= n; ++i) {		cal(a, b, i, x);		if (b != 0) now = 1.0 * a / b;		else now = -1.0;		if (ans_num == -1.0 || (ans_num != -1.0 && now != -1.0 && now <= ans_num))			if (fabs(ans_num - now) < 1e-12) {				if (h[i] > h[ans]) ans = i;			} else ans_num = now, ans = i;	}	printf("%d\n", ans);		m = in(); int i = 0;	while (m--) {		++i;		s = in(); x = in();		cal(a, b, s, x);		printf("%d %d\n", a, b);	}		return 0;}

_(:з」∠)_

【CodeVS 1199】【NOIP 2012】开车旅行