poj 2777 Count Color(线段树)

#include <cstdio>
#include <iostream>
using namespace std;

const int MAX_N = 4 * 100000 + 100;
unsigned cnt[MAX_N], set[MAX_N];
unsigned ans = 0;

int Max(int a, int b) { return a > b ? a : b; }
int Min(int a, int b) { return a < b ? a : b; }
void PushDown(int o)
{
    int lc = 2 * o, rc = 2 * o + 1;
    if (set[o] > 0)
    {
        set[lc] = set[rc] = set[o];
        cnt[lc] = cnt[rc] = set[o];
        set[o] = 0;
    }
}

void Maintain(int o)
{
    int lc = 2 * o, rc = 2 * o + 1;
    cnt[o] = cnt[lc] | cnt[rc];
}

void Build(int o, int l, int r)
{
    set[o] = 0;
    if (l == r)
        cnt[o] = 1;
    else
    {
        int mid = (l + r) / 2;
        Build(2 * o, l, mid);
        Build(2 * o + 1, mid + 1, r);
        Maintain(o);
    }
}

void Updata(int o, int l, int r, unsigned color, int ql, int qr)
{
    if (ql <= l && r <= qr)
        set[o] = cnt[o] = color;
    else
    {
        PushDown(o);

        int mid = (l + r) / 2;
        if (ql <= mid)
            Updata(2 * o, l, mid, color, ql, qr);
        if (mid < qr)
            Updata(2 * o + 1, mid + 1, r, color, ql, qr);
        Maintain(o);
    }
}

void Query(int o, int l, int r, int ql, int qr)
{
    if (ql <= l && r <= qr)
        ans |= cnt[o];
    else
    {
        PushDown(o);
        int mid = (l + r) / 2;
        if (mid >= ql)
            Query(2 * o, l, mid, ql, qr);
        if (mid < qr)
            Query(2 * o + 1, mid + 1, r, ql, qr);
    }
}

int main()
{
    int num, color_num, op_num;

    scanf("%d %d %d", &num, &color_num, &op_num);
    Build(1, 1, num);
    for (int i = 0; i < op_num; ++i)
    {
        int ql, qr;
        unsigned color = 0;
        char str[2];

        scanf("%s", str);
        if (str[0] == ‘C‘)
        {
            int temp_l, temp_r;
            scanf("%d %d %d", &temp_l, &temp_r, &color);

            ql = Min(temp_l, temp_r);
            qr = Max(temp_l, temp_r);
            color = 1 << (color - 1);
            Updata(1, 1, num, color, ql, qr);
        }
        else
        {
            int temp = 0, temp_l, temp_r;

            ans = 0;
            scanf("%d %d", &temp_l, &temp_r);

            ql = Min(temp_l, temp_r);
            qr = Max(temp_l, temp_r);
            Query(1, 1, num, ql, qr);
            while (ans)
            {
                temp += ans & 1;
                ans >>= 1;
            }
            printf("%d\n", temp);
        }
    }
    return 0;
}