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HDU 3911 线段树区间合并
北京赛区快了,准备突击数据结构和图论,倒计时 18天,线段树区间合并,维护一个最长连续。。
题意:给一个01串,下面有一些操作,问区间最长的连续的1的个数
思路:很裸的线段树区间合并
#include<iostream> #include<cstdio> #include<map> #include<set> #include<cmath> #define lson id << 1 #define rson id << 1|1 using namespace std; const int M = 1e6+8; int a[M]; struct tree{ int l,r; int rsum1,lsum1,msum1,lsum0,rsum0,msum0; int flag; int mid(){ return (l+r)/2; } }node[M]; void pushdown(int id){ if(node[id].flag){ node[lson].flag ^= 1; node[rson].flag ^= 1; node[id].flag = 0; swap(node[lson].lsum1,node[lson].lsum0); swap(node[lson].rsum1,node[lson].rsum0); swap(node[lson].msum1,node[lson].msum0); swap(node[rson].lsum1,node[rson].lsum0); swap(node[rson].rsum1,node[rson].rsum0); swap(node[rson].msum1,node[rson].msum0); } } void pushup(int id){ int ll = node[lson].r-node[lson].l + 1; int rl = node[rson].r-node[rson].l + 1; node[id].lsum1 = node[lson].lsum1; if(node[lson].lsum1 == ll)node[id].lsum1 += node[rson].lsum1; node[id].rsum1 = node[rson].rsum1; if(node[rson].rsum1 == rl)node[id].rsum1 += node[lson].rsum1; node[id].msum1 = max(max(node[rson].msum1,node[lson].msum1),node[lson].rsum1+node[rson].lsum1); node[id].lsum0 = node[lson].lsum0; if(node[lson].lsum0 == ll)node[id].lsum0 += node[rson].lsum0; node[id].rsum0 = node[rson].rsum0; if(node[rson].rsum0 == rl)node[id].rsum0 += node[lson].rsum0; node[id].msum0 = max(max(node[rson].msum0,node[lson].msum0),node[lson].rsum0+node[rson].lsum0); } void build(int l,int r,int id){ node[id].l = l; node[id].r = r; node[id].flag = 0; if(l == r){ if(a[l] == 1){ node[id].lsum1 = node[id].rsum1 = node[id].msum1 = 1; node[id].lsum0 = node[id].rsum0 = node[id].msum0 = 0; }else{ node[id].lsum1 = node[id].rsum1 = node[id].msum1 = 0; node[id].lsum0 = node[id].rsum0 = node[id].msum0 = 1; } return; } int mid = node[id].mid(); build(l,mid,lson); build(mid+1,r,rson); pushup(id); } void update(int id,int l,int r){ if(node[id].l == l && node[id].r == r){ node[id].flag ^= 1; swap(node[id].lsum1,node[id].lsum0); swap(node[id].rsum1,node[id].rsum0); swap(node[id].msum1,node[id].msum0); return ; } pushdown(id); int mid = node[id].mid(); if(r <= mid)update(lson,l,r); else if(l>mid)update(rson,l,r); else { update(lson,l,mid); update(rson,mid+1,r); } pushup(id); } int query(int id,int l,int r){ if(node[id].l == l && node[id].r ==r){ return node[id].msum1; } pushdown(id); int mid = node[id].mid(); if(r <=mid)return query(lson,l,r); else if(l > mid)return query(rson,l,r); else { int ll = query(lson,l,mid); int rr = query(rson,mid+1,r); int a = node[lson].rsum1; if(a > (node[lson].r - l +1))a = node[lson].r - l +1 ; int b = node[rson].lsum1; if(b > (r - node[rson].l+1))b = r - node[rson].l+1; return max(max(ll,rr),a+b); } } int main(){ int n,m,op,l,r; while(~scanf("%d",&n)){ for(int i=1;i<=n;i++)scanf("%d",&a[i]); build(1,n,1); scanf("%d",&m); while(m--){ scanf("%d%d%d",&op,&l,&r); if(!op)printf("%d\n",query(1,l,r)); else update(1,l,r); } } }
HDU 3911 线段树区间合并
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