POJ 3225 Help with Intervals 线段树区间操作

/*Accepted    2364K    969MS    C++    2769B    2012-08-22 16:54:26*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
using namespace std;
#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1

const int MAXN = 131072;
bool hash[MAXN + 1];
int col[MAXN << 2], XOR[MAXN << 2];
void FXOR(int rt)
{
    if(col[rt] != -1) col[rt] ^= 1;
    else XOR[rt] ^= 1;
}

void PushDown(int rt)
{
    if(col[rt] != -1)
    {
        col[rt << 1] = col[rt << 1 | 1] = col[rt];
        XOR[rt << 1] = XOR[rt << 1 | 1] = 0;
        col[rt] = -1;
    }
    if(XOR[rt])
    {
        FXOR(rt << 1);
        FXOR(rt << 1 | 1);
        XOR[rt] = 0;
    }
}

void update(char op, int L, int R, int l, int r, int rt)
{
    int mid = l + r >> 1;
    if(L <= l && r <= R)
    {
        if(op == 'U')
        {
            col[rt] = 1;
            XOR[rt] = 0;
        }
        else if(op == 'D')
        {
            col[rt] = 0;
            XOR[rt] = 0;
        }
        else if(op == 'C' || op == 'S')
        {
            FXOR(rt);
        }
        return;
    }
    PushDown(rt);
    if(L <= mid) update(op, L, R, lson);
    else if(op == 'I' || op == 'C')
    {
        XOR[rt << 1] = col[rt << 1] = 0;
    }
    if(R > mid) update(op, L, R, rson);
    else if(op == 'I' || op == 'C')
    {
        XOR[rt << 1 | 1] = col[rt << 1 | 1] = 0;
    }
}

void query(int l, int r, int rt)
{
    int i, mid = l + r >> 1;
    if(col[rt] == 1)
    {
        for(i = l; i <= r; i ++)
        {
            hash[i] = true;
        }
        return;
    }
    else if(col[rt] == 0) return;
    if(l == r) return;
    PushDown(rt);
    query(lson);
    query(rson);
}

int main()
{
    col[1] = XOR[1] = 0;
    char op, left, right, str[25];
    int a, b;
    while(gets(str)!= NULL)
    {
        sscanf(str, "%c %c%d,%d%c", &op, &left, &a, &b, &right);
        a <<= 1, b <<= 1;
        if(left == '(') a ++;
        if(right == ')') b --;
        if(a > b)
        {
            if(op == 'C' || op == 'I')
            {
                col[1] = XOR[1] = 0;
            }
        }
        else update(op, a, b, 0, MAXN, 1);
    }
    query(0, MAXN, 1);
    bool flag = false;
    int s = -1, e, i;
    for(i = 0; i <= MAXN; i ++)
    {
        if(hash[i]) {
            if(s == -1) s = i;
            e = i;
        }
        else
        {
            if(s != -1)
            {
                if(flag) printf(" ");
                flag = true;
                printf("%c%d,%d%c", s & 1 ? '(' : '[', s >> 1, e + 1 >> 1,
                                    e & 1 ? ')' : ']');
                s = -1;
            }
        }
    }
    if(!flag) printf("empty set");
    puts("");
    return 0;
}