The art of "luogu P2574"xor--line tree

# Ideas for solving problems

This problem is not difficult, but forgive me the beginning of the silly idea, a moment to reveal to everyone.

Tell me how to do it first.

Obviously, for $0$ and $1$, there are only two variations of XOR.

• $0$ will become $1$,$1$ and will become $0$.
• Different or even several times, $0$ and $1$ are unchanged.

That only needs to be changed a few times when the mark is next passed.

OK, let's talk about my stupid operation. I did not give the sum of the child node an XOR when I passed the tag, but only the tag, and did not update the sum value of the parent node when backtracking.

Then I did not have the success of the example, but goose this is not stupid, and changed to do it, right, but, the silly to come, I changed the time did not follow the above to change, but in the update, along the way to the node hit a flag flag, pretend that this period needs to change.

hahaha haha, then I succeeded in getting a good score of T four points.

What a ghost, I actually forgot to update the parent node, sure enough, I am too much food.

I decided to put this code on.

# Attach Code

Put on my dumb-nuts. Error code

#include <iostream>#include<cstring>#include<cstdio>using namespacestd;intN, M;Const intMAXN = 2e5+3;structNode {intL, R, Sum, T, tag, flag;} TREE[MAXN <<2];structTree {#defineLson (k << 1)#defineRson ((k << 1) | 1)Template<typename t> InlinevoidRead (T &x) {x=0; T f =1;Charc =GetChar ();  while(C <'0'|| C >'9') {if(c = ='-') F =-1; c =GetChar ();}  while(c <='9'&& C >='0') {x = x*Ten+ C'0'; c =GetChar ();} X*=F; }    voidBuildintKintllintRR) {TREE[K].L= ll, TREE[K].R =RR; Tree[k].flag= TREE[K].T =0; if(TREE[K].L = =TREE[K].R) {scanf ("%1d", &tree[k].sum); return ; }        intMid = (tree[k].l + TREE[K].R) >>1;        Build (Lson, TREE[K].L, mid); Build (Rson, mid+1, TREE[K].R); Tree[k].sum= Tree[lson].sum +tree[rson].sum; }    voidPush_down (intk) {tree[lson].t+=Tree[k].tag; TREE[RSON].T+=Tree[k].tag; Tree[lson].tag+=Tree[k].tag; Tree[rson].tag+=Tree[k].tag; Tree[k].tag=0; }    voidUpdateintKintLintR) {if(TREE[K].L >= l && TREE[K].R <=R) {tree[k].t++; Tree[k].tag++; return; } Tree[k].flag=1; if(Tree[k].tag) Push_down (k); intMid = (tree[k].l + TREE[K].R) >>1; if(L <=mid) Update (Lson, L, R); if(R >mid) Update (Rson, L, R); }    intQueryintKintLintR) {intAns =0; if(TREE[K].L >= L && tree[k].r <= r && Tree[k].flag = =0) {            if(tree[k].t%2==1)return(tree[k].r-tree[k].l+1)-tree[k].sum; Else returntree[k].sum; }        if(Tree[k].tag) Push_down (k); intMid = (tree[k].l + TREE[K].R) >>1; if(L <= mid) ans + =query (Lson, L, R); if(R > mid) ans + =query (Rson, L, R); returnans;        } Tree () {read (n), read (m); Build (1,1, N); intopt, l, R;  for(intI=1; i<=m; i++{Read (opt), read (L), read (R); if(opt = =0) Update (1, L, R); Elseprintf"%d\n", Query (1, L, R)); }}}t;intMain () {return 0;}

Okay, let's take a look at the correct code.

#include <iostream>#include<cstring>#include<cstdio>using namespacestd;intN, M;Const intMAXN = 2e5+3;structNode {intL, R, Sum, T, tag, flag;} TREE[MAXN <<2];structTree {#defineLson (k << 1)#defineRson ((k << 1) | 1)Template<typename t> InlinevoidRead (T &x) {x=0; T f =1;Charc =GetChar ();  while(C <'0'|| C >'9') {if(c = ='-') F =-1; c =GetChar ();}  while(c <='9'&& C >='0') {x = x*Ten+ C'0'; c =GetChar ();} X*=F; }    voidBuildintKintllintRR) {TREE[K].L= ll, TREE[K].R =RR; Tree[k].flag= TREE[K].T =0; if(TREE[K].L = =TREE[K].R) {scanf ("%1d", &tree[k].sum); return ; }        intMid = (tree[k].l + TREE[K].R) >>1;        Build (Lson, TREE[K].L, mid); Build (Rson, mid+1, TREE[K].R); Tree[k].sum= Tree[lson].sum +tree[rson].sum; }    voidPush_down (intk) {if(Tree[k].tag%2==1) Tree[lson].sum= (tree[lson].r-tree[lson].l+1)-Tree[lson].sum, Tree[rson].sum= (tree[rson].r-tree[rson].l+1)-tree[rson].sum; Tree[lson].tag+=Tree[k].tag; Tree[rson].tag+=Tree[k].tag; Tree[k].tag=0; }    voidUpdateintKintLintR) {if(TREE[K].L >= l && TREE[K].R <=R) {Tree[k].tag++; Tree[k].sum= (tree[k].r-tree[k].l+1)-tree[k].sum; return; }        if(Tree[k].tag) Push_down (k); intMid = (tree[k].l + TREE[K].R) >>1; if(L <=mid) Update (Lson, L, R); if(R >mid) Update (Rson, L, R); Tree[k].sum= Tree[lson].sum +tree[rson].sum; }    intQueryintKintLintR) {intAns =0; if(TREE[K].L >= l && TREE[K].R <=R)returntree[k].sum; if(Tree[k].tag) Push_down (k); intMid = (tree[k].l + TREE[K].R) >>1; if(L <= mid) ans + =query (Lson, L, R); if(R > mid) ans + =query (Rson, L, R); returnans;        } Tree () {read (n), read (m); Build (1,1, N); intopt, l, R;  for(intI=1; i<=m; i++{Read (opt), read (L), read (R); if(opt = =0) Update (1, L, R); Elseprintf"%d\n", Query (1, L, R)); }}}t;intMain () {return 0;}

The art of "luogu P2574"xor--line tree