POJ 1436 Horizontally Visible Segments 线段树 成段更新

#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn = 8000<<1;
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define mid int m = (l + r)>>1
int n;
int col[maxn<<2];
int vis[maxn<<2];
vector<int> ans[maxn];
struct node
{
    int y1, y2, x;
}p[maxn];
bool cmp(node a, node b)
{
    return a.x < b.x;
}
void pushdown(int rt)
{
    if(col[rt])
    {
        col[rt<<1] = col[rt<<1|1] = col[rt];
        col[rt] = 0;
    }
}

void query(int L, int R, int v, int l, int r, int rt)
{
    if(col[rt])
    {
        if(vis[col[rt]] != v)
        {
            vis[col[rt]] = v;
            ans[col[rt]].push_back(v);
        }
        return;
    }
    if(l == r) return;
    mid;
    if(L <= m) query(L, R, v, lson);
    if(R > m) query(L, R, v, rson);
}
void update(int L, int R, int v, int l, int r, int rt)
{
    if(L <= l && r <= R)
    {
        col[rt] = v;
        return;
    }
    pushdown(rt);
    mid;
    if(L <= m) update(L, R, v, lson);
    if(R > m) update(L, R, v, rson);
}

void debug()
{
    int i, j;
    for(i = 1; i <= n; i++)
    {
        printf("%d : ", i);
        for(j = 0 ; j < ans[i].size(); j++)
            printf("%d ", ans[i][j]);
        puts("");
    }
}
int main()
{
    int i, j, cas;
    scanf("%d", &cas);
    while(cas--)
    {
        scanf("%d", &n);
        for(i = 1; i <= n; i++)
            ans[i].clear();
        memset(col, 0, sizeof(col));
        memset(vis, 0, sizeof(vis));
        for(i = 1; i <= n; i++)
            scanf("%d%d%d", &p[i].y1, &p[i].y2, &p[i].x);
        sort(p+1, p+n+1, cmp);
        for(i = 1; i <= n; i++)
        {
            p[i].y1 <<= 1; p[i].y2 <<= 1;
            query(p[i].y1, p[i].y2, i, 0, maxn-1, 1);
            update(p[i].y1, p[i].y2, i, 0, maxn-1, 1);
        }
        int cnt = 0;
      //  debug();
        for(i = 1; i <= n; i++)
            for(j = 0; j < ans[i].size(); j++)
            {
                int u = ans[i][j];
                for(int x = 0; x < ans[i].size(); x++)
                    for(int y = 0; y < ans[u].size(); y++)
                        if(ans[i][x] == ans[u][y])
                            cnt++;
            }
                            
        printf("%d\n", cnt);
    }
    return 0;
}