链接；http://acm.hdu.edu.cn/showproblem.php?pid=3397
题意：
给你一串01串，有5种操作
0. 区间全部变为0
1.区间全部变为1
2.区间异或
3.询问区间1的个数
4.询问区间被最长连续1的长度
思路：
这5个操作都是比较基础的线段树操作，难点在于有两种修改操作，这类题之前也写过，之前是乘法和加法，这个是区间亦或和区间更新值，但是思路是可以借鉴的，我们要推出这两个操作的关系，这样才能维护好这两个标记，我们用两个标记：same , rev ，分别表示区间更新值和区间异或，那么向下更新的时候如果如果有same标记，清空当前区间的rev标记，简单维护下就好了，如果有rev标记，且有same标记，那么直接对same异或维护，如果没有same标记那么就维护下区间异或就好了。
写的超爽，一遍就a了，美滋滋，还以为又要找好久的错。。
实现代码：
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define mid int m = (l + r) >> 1
#define ll long long
const int M = 1e5 + 10;
int lsum1[M<<2],rsum1[M<<2],sum1[M<<2];
int lsum0[M<<2],rsum0[M<<2],sum0[M<<2];
int sum[M<<2],same[M<<2],rev[M<<2];
int a[M];
void pushup(int l,int r,int rt){
mid;
sum[rt] = sum[rt<<1] + sum[rt<<1|1];
lsum0[rt] = lsum0[rt<<1]; lsum1[rt] = lsum1[rt<<1];
rsum0[rt] = rsum0[rt<<1|1]; rsum1[rt] = rsum1[rt<<1|1];
if(lsum0[rt] == m-l+1) lsum0[rt] += lsum0[rt<<1|1];
if(rsum0[rt] == r-m) rsum0[rt] += rsum0[rt<<1];
if(lsum1[rt] == m-l+1) lsum1[rt] += lsum1[rt<<1|1];
if(rsum1[rt] == r-m) rsum1[rt] += rsum1[rt<<1];
sum0[rt] = max(max(sum0[rt<<1],sum0[rt<<1|1]),lsum0[rt<<1|1]+rsum0[rt<<1]);
sum1[rt] = max(max(sum1[rt<<1],sum1[rt<<1|1]),lsum1[rt<<1|1]+rsum1[rt<<1]);
}
void swa(int len,int rt){
sum[rt] = len - sum[rt];
swap(lsum1[rt],lsum0[rt]);
swap(rsum1[rt],rsum0[rt]);
swap(sum1[rt],sum0[rt]);
}
void pushdown(int l,int r,int rt){
mid;
if(same[rt]!=-1){
rev[rt<<1] = rev[rt<<1|1] = 0;
same[rt<<1] = same[rt<<1|1] = same[rt];
if(same[rt]){
sum[rt<<1] = lsum1[rt<<1] = rsum1[rt<<1] = sum1[rt<<1] = m-l+1;
sum[rt<<1|1] = lsum1[rt<<1|1] = rsum1[rt<<1|1] = sum1[rt<<1|1] = r-m;
lsum0[rt<<1] = rsum0[rt<<1] = sum0[rt<<1] = sum0[rt<<1|1] = rsum0[rt<<1|1] = lsum0[rt<<1|1] = 0;
}
else{
sum[rt<<1] = lsum1[rt<<1] = rsum1[rt<<1] = sum1[rt<<1] = 0;
sum[rt<<1|1] = lsum1[rt<<1|1] = rsum1[rt<<1|1] = sum1[rt<<1|1] = 0;
lsum0[rt<<1] = rsum0[rt<<1] = sum0[rt<<1] = m-l+1;
sum0[rt<<1|1] = rsum0[rt<<1|1] = lsum0[rt<<1|1] = r-m;
}
same[rt] = -1;
}
if(rev[rt]){
if(same[rt<<1] != -1){
same[rt<<1] ^= 1;
if(same[rt<<1]){
sum[rt<<1] = lsum1[rt<<1] = rsum1[rt<<1] = sum1[rt<<1] = m-l+1;
lsum0[rt<<1] = rsum0[rt<<1] = sum0[rt<<1] = 0;
}
else{
sum[rt<<1] = lsum1[rt<<1] = rsum1[rt<<1] = sum1[rt<<1] = 0;
lsum0[rt<<1] = rsum0[rt<<1] = sum0[rt<<1] = m-l+1;
}
}
else{
rev[rt<<1] ^= 1;
swa(m-l+1,rt<<1);
}
if(same[rt<<1|1] != -1){
same[rt<<1|1] ^= 1;
if(same[rt<<1|1]){
sum[rt<<1|1] = lsum1[rt<<1|1] = rsum1[rt<<1|1] = sum1[rt<<1|1] = r-m;
sum0[rt<<1|1] = rsum0[rt<<1|1] = lsum0[rt<<1|1] = 0;
}
else{
sum[rt<<1|1] = lsum1[rt<<1|1] = rsum1[rt<<1|1] = sum1[rt<<1|1] = 0;
sum0[rt<<1|1] = rsum0[rt<<1|1] = lsum0[rt<<1|1] = r-m;
}
}
else{
rev[rt<<1|1] ^= 1;
swa(r-m,rt<<1|1);
}
rev[rt] = 0;
}
}
void build(int l,int r,int rt){
same[rt] = -1; rev[rt] = 0;
lsum1[rt] = rsum1[rt] = lsum0[rt] = rsum0[rt] = sum0[rt] = sum1[rt] = sum[rt] = 0;
if(l == r){
if(a[l]){
lsum1[rt] = sum[rt] = sum1[rt] = rsum1[rt] = 1;
lsum0[rt] = rsum0[rt] = sum0[rt] = 0;
}
else {
sum1[rt] = sum[rt] = sum1[rt] = rsum1[rt] = 0;
lsum0[rt] = rsum0[rt] = sum0[rt] = 1;
}
return ;
}
mid ;
build(lson); build(rson);
pushup(l,r,rt);
}
void update_same(int L,int R,int c,int l,int r,int rt){
if(L <= l&&R >= r){
rev[rt] = 0;
same[rt] = c;
if(same[rt]){
sum[rt] = lsum1[rt] = rsum1[rt] = sum1[rt] = r-l+1;
lsum0[rt] = rsum0[rt] = sum0[rt] = 0;
}
else{
sum[rt] = lsum1[rt] = rsum1[rt] = sum1[rt] = 0;
lsum0[rt] = rsum0[rt] = sum0[rt] = r-l+1;
}
return ;
}
pushdown(l,r,rt);
mid;
if(L <= m) update_same(L,R,c,lson);
if(R > m) update_same(L,R,c,rson);
pushup(l,r,rt);
}
void update_rev(int L,int R,int l,int r,int rt){
if(L <= l&&R >= r){
if(same[rt] != -1){
same[rt] ^= 1;
if(same[rt]){
sum[rt] = lsum1[rt] = rsum1[rt] = sum1[rt] = r-l+1;
lsum0[rt] = rsum0[rt] = sum0[rt] = 0;
}
else{
sum[rt] = lsum1[rt] = rsum1[rt] = sum1[rt] = 0;
lsum0[rt] = rsum0[rt] = sum0[rt] = r-l+1;
}
}
else{
rev[rt] ^= 1;
swa(r-l+1,rt);
}
return ;
}
mid ;
pushdown(l,r,rt);
if(L <= m) update_rev(L,R,lson);
if(R > m) update_rev(L,R,rson);
pushup(l,r,rt);
}
int query_sum(int L,int R,int l,int r,int rt){
if(L <= l&&R >= r){
return sum[rt];
}
pushdown(l,r,rt);
mid;
int ret = 0;
if(L <= m) ret += query_sum(L,R,lson);
if(R > m) ret += query_sum(L,R,rson);
return ret;
}
int query_max(int L,int R,int l,int r,int rt){
if(L <= l&&R >= r){
return sum1[rt];
}
pushdown(l,r,rt);
mid;
int ret = 0;
if(L > m) return query_max(L,R,rson);
if(R <= m) return query_max(L,R,lson);
int t1 = query_max(L,R,lson);
int t2 = query_max(L,R,rson);
int ls = min(rsum1[rt<<1],m-L+1);
int rs = min(lsum1[rt<<1|1],R-m);
return max(max(t1,t2),ls+rs);
}
int main()
{
int n,q,x,y,op,t;
scanf("%d",&t);
while(t--){
scanf("%d%d",&n,&q);
for(int i = 1;i <= n;i ++)
scanf("%d",&a[i]);
build(1,n,1);
while(q--){
scanf("%d%d%d",&op,&x,&y);
x++; y++;
if(op == 0){
update_same(x,y,0,1,n,1);
}
else if(op == 1){
update_same(x,y,1,1,n,1);
}
else if(op == 2){
update_rev(x,y,1,n,1);
}
else if(op == 3){
printf("%d\n",query_sum(x,y,1,n,1));
}
else {
printf("%d\n",query_max(x,y,1,n,1));
}
}
}
return 0;
}
原文地址：https://www.cnblogs.com/kls123/p/9781070.html
时间： 2024-11-17 18:26:04