【BZOJ 1230】 开关灯

【题目链接】

            https://www.lydsy.com/JudgeOnline/problem.php?id=1230

【算法】

           线段树

【代码】

            

#include<bits/stdc++.h>
using namespace std;
#define MAXN 100010

int n,m,l,r,opt;

struct Node
{
        int l,r,sum;
        bool tag;
};

class SegmentTree
{
        private :
                Node Tree[MAXN<<2];
        public :
              inline void build(int index,int l,int r)
              {
                      int mid;
                      Tree[index].l = l; Tree[index].r = r;
                      Tree[index].sum = 0;
                        Tree[index].tag = false;
                      if (l == r) return;
                      mid = (l + r) >> 1;
                      build(index<<1,l,mid);
                      build(index<<1|1,mid+1,r);
                }
                inline void update(int index)
                {
                        Tree[index].sum = Tree[index<<1].sum + Tree[index<<1|1].sum;
                }
                inline void pushdown(int index)
                {
                        int l = Tree[index].l,r = Tree[index].r;
                        int mid = (l + r) >> 1;
                        if (Tree[index].tag)
                        {
                                Tree[index<<1].sum = mid - l + 1 - Tree[index<<1].sum;
                                Tree[index<<1|1].sum = r - mid - Tree[index<<1|1].sum;
                                Tree[index<<1].tag ^= 1;
                                Tree[index<<1|1].tag ^= 1;
                                Tree[index].tag = false;
                        }
                }
                inline void modify(int index,int l,int r)
                {
                        int mid;
                        if (Tree[index].l == l && Tree[index].r == r)
                        {
                                Tree[index].sum = r - l + 1 - Tree[index].sum;
                                Tree[index].tag ^= 1;
                                return;
                        } else
                        {
                                pushdown(index);
                                mid = (Tree[index].l + Tree[index].r) >> 1;
                                if (mid >= r) modify(index<<1,l,r);
                                else if (mid + 1 <= l) modify(index<<1|1,l,r);
                                else
                                {
                                        modify(index<<1,l,mid);
                                        modify(index<<1|1,mid+1,r);
                                } 
                                update(index);
                        }
                }
                inline int query(int index,int l,int r)
                {
                        int mid;
                        if (Tree[index].l == l && Tree[index].r == r) return Tree[index].sum;
                        else
                        {
                                pushdown(index);
                                mid = (Tree[index].l + Tree[index].r) >> 1;
                                if (mid >= r) return query(index<<1,l,r);
                                else if (mid + 1 <= l) return query(index<<1|1,l,r);
                                else return query(index<<1,l,mid) + query(index<<1|1,mid+1,r);
                        }
                }
} T;

int main() 
{
        
        scanf("%d%d",&n,&m);
        T.build(1,1,n);
        while (m--)
        {
                scanf("%d%d%d",&opt,&l,&r);
                if (opt == 0) T.modify(1,l,r);
                else printf("%d\n",T.query(1,l,r));        
        }
        
        return 0;
    
}