poj 2892 || hdu 1540 Tunnel Warfare

来源：互联网发布：php是做什么用的编辑：程序博客网时间：2024/06/03 11:15

又是找区间最长的什么什么的。和hotel前期处理差不多。都需要记录从左边开始的连续的最大值，从右边开始的连续最大值，以及整个区间的最大值。

不同的是，这个题的R D操作都是基于点的操作，所以不需要用 lazy思想了，直接更新到底。

至于查询，纠结了，参考了别人的代码，我发现我脑子还是有点转不过来哎。。。其实那种做法也想到了，就是感觉有点麻烦 = =。。。

注意查询临界情况，已经摧毁的用栈存了即可。

#include <queue>#include <stack>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <iostream>#include <limits.h>#include <string.h>#include <string>#include <algorithm>#define MID(x,y) ( ( x + y ) >> 1 )#define L(x) ( x << 1 )#define R(x) ( x << 1 | 1 )#define BUG puts("here!!!")using namespace std;const int MAX = 50010;struct Tnode{ int cover,l,r,lval,rval,sum;};Tnode node[MAX<<2];stack<int> s;void init(){memset(node,0,sizeof(node));}void Build(int t,int l,int r){node[t].l = l; node[t].r = r;node[t].lval = node[t].rval = node[t].sum = r - l;node[t].cover = 1;if( l == r - 1 ) return ;int mid = MID(l,r);Build(L(t),l,mid);Build(R(t),mid,r);}void Updata_sum(int t){if( node[R(t)].cover == 0 && node[L(t)].cover == 0 )node[t].cover = 0;elseif( node[R(t)].cover == 1 && node[L(t)].cover == 1 )node[t].cover = 1;elsenode[t].cover = -1;node[t].lval = node[L(t)].lval + ( node[L(t)].cover == 1 ? node[R(t)].lval : 0 );node[t].rval = node[R(t)].rval + ( node[R(t)].cover == 1 ? node[L(t)].rval : 0 );node[t].sum = max(node[t].rval,max(node[t].lval,node[L(t)].rval + node[R(t)].lval));}void Updata(int t,int l,int r,int val){if( node[t].l >= l && node[t].r <= r ){node[t].cover = node[t].lval = node[t].rval = node[t].sum = val;return ;}if( node[t].l == node[t].r - 1 ) return ;int mid = MID(node[t].l,node[t].r);if( l <= mid )Updata(L(t),l,r,val);if( r > mid )Updata(R(t),l,r,val);Updata_sum(t);}int Query(int t,int l){if( node[t].cover == 1 ) return node[t].sum;if( node[t].cover == 0 ) return 0;int mid = MID(node[t].l,node[t].r);if( l < mid ){if( mid - l <= node[L(t)].rval )return node[L(t)].rval + node[R(t)].lval;return Query(L(t),l);}else{if( l - mid + 1 <= node[R(t)].lval )return node[L(t)].rval + node[R(t)].lval;return Query(R(t),l);}}int main(){int n,m,x;char ch[2];while( ~scanf("%d%d",&n,&m) ){init();Build(1,0,n);while( !s.empty() ) s.pop();while( m-- ){scanf("%s",ch);if( ch[0] == 'D' ){scanf("%d",&x);Updata(1,x-1,x,0);s.push(x);}if( ch[0] == 'R' ){if( s.empty() ) break;x = s.top(); s.pop();Updata(1,x-1,x,1);}if( ch[0] == 'Q' ){scanf("%d",&x);int ans = Query(1,x-1);printf("%d\n",ans);}}}return 0;}