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不得不说,这是一题非常经典的体积并。。然而还是debug了2个多小时...
首先思路:按z的大小排序。
然后相当于扫描面一样,,从体积的最下方向上方扫描,遇到这个面
就将对应的两条线加入到set中,或者从set中删除,然后再对set中的所有边,求一次面积并
由于最后求出来的是至少有3个体积叠加的部分的体积。
所以需要维护3个节点,然后push_up会稍微啰嗦一点...
刚开始在set插入线段和删除线段的时候,搞错了线段所在面的编号,,然后一直样例都过不去也是醉了...
总的来说代码比较冗长需要足够细心才能敲对..
#include<map> #include<set> #include<cmath> #include<stack> #include<queue> #include<cstdio> #include<string> #include<vector> #include<cstring> #include<iostream> #include<algorithm> #include<functional> using namespace std; typedef long long LL; typedef pair<int, int> PII; #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #define root 1,rear-1,1 int const MX = 4e3 + 5; struct Side { int z, x1, y1, x2, y2, d, id; bool operator<(const Side &b)const { if(z == b.z) return d < b.d; return z < b.z; } Side() {} Side(int _z, int _id, int _x1, int _y1, int _x2, int _y2, int _d) { z = _z; x1 = _x1; y1 = _y1; x2 = _x2; y2 = _y2; d = _d; id = _id; } } A[MX]; struct Line { int y, x1, x2, d, id; bool operator<(const Line &b)const { if(y == b.y) { if(d == b.d) return id < b.id; return d < b.d; } return y < b.y; } Line() {} Line(int _y, int _id, int _d, int _x1, int _x2) { y = _y; x1 = _x1; x2 = _x2; d = _d; id = _id; } }; int X[MX], rear; int S1[MX << 2], S2[MX << 2], S3[MX << 2], cnt[MX << 2]; set<Line>work; int BS(int x) { int L = 1, R = rear, m; while(L <= R) { m = (L + R) >> 1; if(X[m] == x) return m; if(X[m] > x) R = m - 1; else L = m + 1; } return -1; } void push_up(int l, int r, int rt) { if(cnt[rt]) { S1[rt] = X[r + 1] - X[l]; if(cnt[rt] == 1) { S2[rt] = S1[rt << 1] + S1[rt << 1 | 1]; S3[rt] = S2[rt << 1] + S2[rt << 1 | 1]; } else { S2[rt] = X[r + 1] - X[l]; if(cnt[rt] == 2) { S3[rt] = S1[rt << 1] + S1[rt << 1 | 1]; } else { S3[rt] = X[r + 1] - X[l]; } } } else if(l == r) S1[rt] = S2[rt] = S3[rt] = 0; else { S1[rt] = S1[rt << 1] + S1[rt << 1 | 1]; S2[rt] = S2[rt << 1] + S2[rt << 1 | 1]; S3[rt] = S3[rt << 1] + S3[rt << 1 | 1]; } } void update(int L, int R, int d, int l, int r, int rt) { if(L <= l && r <= R) { cnt[rt] += d; push_up(l, r, rt); return; } int m = (l + r) >> 1; if(L <= m) update(L, R, d, lson); if(R > m) update(L, R, d, rson); push_up(l, r, rt); } LL solve() { memset(S1, 0, sizeof(S1)); memset(S2, 0, sizeof(S2)); memset(cnt, 0, sizeof(cnt)); LL ans = 0; int last = 0; for(set<Line>::iterator it = work.begin(); it != work.end(); it++) { ans += (LL)(it->y - last) * S3[1]; update(BS(it->x1), BS(it->x2) - 1, it->d, root); last = it->y; } return ans; } int main() { //freopen("input.txt", "r", stdin); int T, n, ansk = 0; scanf("%d", &T); while(T--) { rear = 0; work.clear(); scanf("%d", &n); for(int i = 1; i <= n; i++) { int x1, y1, z1, x2, y2, z2; scanf("%d%d%d%d%d%d", &x1, &y1, &z1, &x2, &y2, &z2); A[i] = Side(z1, i, x1, y1, x2, y2, 1); A[i + n] = Side(z2, i, x1, y1, x2, y2, -1); X[++rear] = x1; X[++rear] = x2; } sort(A + 1, A + 1 + 2 * n); sort(X + 1, X + 1 + rear); rear = unique(X + 1, X + 1 + rear) - X - 1; LL ans = 0; int last = 0; printf("Case %d: ", ++ansk); for(int i = 1; i <= 2 * n; i++) { ans += (LL)(A[i].z - last) * solve(); if(A[i].d > 0) { work.insert(Line(A[i].y1, A[i].id, 1, A[i].x1, A[i].x2)); work.insert(Line(A[i].y2, A[i].id, -1, A[i].x1, A[i].x2)); } else { work.erase(Line(A[i].y1, A[i].id, 1, A[i].x1, A[i].x2)); work.erase(Line(A[i].y2, A[i].id, -1, A[i].x1, A[i].x2)); } last = A[i].z; } printf("%I64d\n", ans); } return 0; }
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原文地址:http://blog.csdn.net/qwb492859377/article/details/47441975