HDU1542 Atlantis

线段树扫描线模板

#include <bits/stdc++.h>
#define INF 0x3f3f3f3f
#define full(a, b) memset(a, b, sizeof a)
#define __fastIn ios::sync_with_stdio(false), cin.tie(0)
#define pb push_back
using namespace std;
typedef long long LL;
inline int lowbit(int x){ return x & (-x); }
inline int read(){
    int ret = 0, w = 0; char ch = 0;
    while(!isdigit(ch)){
        w |= ch == '-', ch = getchar();
    }
    while(isdigit(ch)){
        ret = (ret << 3) + (ret << 1) + (ch ^ 48);
        ch = getchar();
    }
    return w ? -ret : ret;
}
template <typename A>
inline A __lcm(A a, A b){ return a / __gcd(a, b) * b; }
template <typename A, typename B, typename C>
inline A fpow(A x, B p, C lyd){
    A ans = 1;
    for(; p; p >>= 1, x = 1LL * x * x % lyd)if(p & 1)ans = 1LL * x * ans % lyd;
    return ans;
}
const int N = 200;
int n, k, cnt[N<<3], cs;
double b[N<<2], sum[N<<3];
struct Seg{
    double l, r, h;
    int tag;
    Seg(){}
    Seg(double l, double r, double h, int tag): l(l), r(r), h(h), tag(tag){}
    bool operator < (const Seg &rhs) const {
        return h < rhs.h;
    }
};
vector<Seg> v;

void push_up(int rt, int l, int r){
    if(cnt[rt]) sum[rt] = b[r + 1] - b[l];
    else if(l == r) sum[rt] = 0;
    else sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];
}

void buildTree(int rt, int l, int r){
    if(l == r){
        cnt[rt] = sum[rt] = 0;
        return;
    }
    int mid = (l + r) >> 1;
    buildTree(rt << 1, l, mid);
    buildTree(rt << 1 | 1, mid + 1, r);
}

void insert(int rt, int l, int r, int il, int ir, int val){
    if(l == il && r == ir){
        cnt[rt] += val;
        push_up(rt, l, r);
        return;
    }
    int mid = (l + r) >> 1;
    if(ir <= mid) insert(rt << 1, l, mid, il, ir, val);
    else if(il > mid) insert(rt << 1 | 1, mid + 1, r, il, ir, val);
    else insert(rt << 1, l, mid, il, mid, val), insert(rt << 1 | 1, mid + 1, r, mid + 1, ir, val);
    push_up(rt, l, r);
}

void init(){
    k = 0;
    v.clear(), full(b, 0);
    full(sum, 0), full(cnt, 0);
}

int main(){

    double x1, y1, x2, y2;
    while(~scanf("%d", &n) && n){
        init();
        for(int i = 1; i <= n; i ++){
            scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
            v.emplace_back(x1, x2, y1, 1);
            v.emplace_back(x1, x2, y2, -1);
            b[++k] = x1, b[++k] = x2;
        }
        sort(b + 1, b + k + 1);
        k = (int)(unique(b + 1, b + k + 1) - b - 1);
        sort(v.begin(), v.end());
        buildTree(1, 1, k - 1);
        double ans = 0;
        for(int i = 0; i < v.size() - 1; i ++){
            int l = (int)(lower_bound(b + 1, b + k + 1, v[i].l) - b);
            int r = (int)(lower_bound(b + 1, b + k + 1, v[i].r) - b);
            r --;
            insert(1, 1, k - 1, l, r, v[i].tag);
            ans += sum[1] * (v[i + 1].h - v[i].h);
        }
        printf("Test case #%d
Total explored area: %.2lf

", ++ cs, ans);
    }
    return 0;
}