POJ 2777 Count Color

线段树。各种WA。最后过了，老泪纵横。

#include <stdio.h>
#define MAXN 100001
int col[MAXN * 4],lazy[MAXN * 4];
void update(int cur)
{
    col[cur] = col[cur << 1] | col[cur << 1 | 1];
}

void pushdown(int cur,int x,int y)
{
    int mid = (x + y) >> 1,ls = cur << 1,rs = cur << 1 | 1;
    if(lazy[cur] != -1)
    {
        lazy[ls] = lazy[cur];
        lazy[rs] = lazy[cur];
        col[ls] = lazy[cur];
        col[rs] = lazy[cur];
        lazy[cur] = -1;
    }
}

void build(int cur,int x,int y)
{
    int mid = (x + y) >> 1,ls = cur << 1,rs = cur << 1 | 1;
    lazy[cur] = -1;
    if(x == y)
    {
        col[cur] = 1;
        return;
    }
    build(ls,x,mid);
    build(rs,mid + 1,y);
    update(cur);
}

void change(int cur,int x,int y,int s,int t,int c)
{
    int mid = (x + y) >> 1,ls = cur << 1,rs = cur << 1 | 1;
    if(x >= s && y <= t)
    {
        col[cur] = c;
        lazy[cur] = c;
        return;
    }
    pushdown(cur,x,y);
    if(mid >= s)
        change(ls,x,mid,s,t,c);
    if(mid + 1 <= t)
        change(rs,mid + 1,y,s,t,c);
    update(cur);
}

void query(int cur,int x,int y,int s,int t,int &ans)
{
    int mid = (x + y) >> 1,ls = cur << 1,rs = cur << 1 | 1;
    
    if(x >= s && y <= t)
    {
        ans |= col[cur];
        return;
    }
    pushdown(cur,x,y);
    if(mid >= s)
        query(ls,x,mid,s,t,ans);
    if(mid + 1 <= t)
        query(rs,mid + 1,y,s,t,ans);
    //update(cur);    
}

int cal(int a)
{
    int ans = 0;
    while(a)
    {
        if(a % 2)
            ans++;
        a >>= 1;
    }
    return ans;
}

int main()
{
    int L,O,T,a,b,c,ans,temp;
    char ch;
    while(scanf("%d%d%d",&L,&T,&O) == 3)
    {
        build(1,1,L);
        while(O--)
        {
            /*printf("\n");
            for(int i = 0;i <= L * 4;i++)
                printf("%d   ",col[i]);
            printf("\n");*/
            getchar();
            scanf("%c",&ch);
            if(ch == 'C')
            {
                scanf("%d%d%d",&a,&b,&c);
                if(a > b)
                {
                    temp = a;
                    a = b;
                    b = temp;
                }
                change(1,1,L,a,b,1 << (c - 1));
            }
            else
            {
                scanf("%d%d",&a,&b);
                if(a > b)
                {
                    temp = a;
                    a = b;
                    b = temp;
                }
                ans = 0;
                query(1,1,L,a,b,ans);
                printf("%d\n",cal(ans));
            }
            /*printf("\n");
            for(int i = 0;i <= L * 4;i++)
                printf("%d   ",col[i]);
            printf("\n");
            for(int i = 0;i <= L * 4;i++)
                printf("%d ",lazy[i]);
            printf("\n");*/
        }
    }
    return 0;
}