poj 1151-atlantis-线段树扫描线求面积并

 = =||好像放在草稿箱里长毛了~~~~~本来想写个好详细好详细的扫描线哒~~~可是看到代码都不想动了，再跟别的大牛的代码一比较，觉得自己这单点更新简直就是纯暴力伪线段树吖~~~还有那离散化【离散了还用函数去O（n）地找是怎么回事啊喂！】如果题目范围是10000个点估计我就布吉岛爆到哪里去了。。。。。所以还是不要教坏小孩子了~~看到这篇日志的童鞋默默转台就好。。。。其实100个点乖乖按线段存然后暴力就好~~~~吐槽完毕~~以上！

AC代码:

  1 #include <iostream>

  2 #include <cstdio>

  3 #include <algorithm>

  4 #include <vector>

  5 using namespace std;

  6 #define maxn 300

  7 #define lson l, m, rt<<1

  8 #define rson m+1, r, rt<<1|1

  9 struct st

 10 {

 11     int cover;

 12     double len;

 13 };

 14 vector<st> sgt;

 15 int n;

 16 struct Line

 17 {

 18     double x, y_up, y_down;

 19     int sign;

 20     bool operator < (const Line that) const {

 21         return x < that.x;

 22     }

 23 };

 24 vector<Line> line;

 25 vector<double> Y;

 26 void input()

 27 {

 28     line.clear();

 29     Y.clear();

 30     sgt.clear();

 31     sgt.resize(maxn<<1);

 32     double x, y, a, b;

 33     Line read;

 34     scanf("%lf%lf%lf%lf", &x, &y, &a, &b);

 35     read.x = x; read.sign = 1; read.y_down = y; read.y_up = b;

 36     line.push_back(read); Y.push_back(y);

 37     read.x = a; read.sign = -1;

 38     line.push_back(read); Y.push_back(b);

 39     for(int i = 1; i < n; i++) {

 40         scanf("%lf%lf%lf%lf", &x, &y, &a, &b);

 41         read.x = x; read.sign = 1; read.y_down = y; read.y_up = b;

 42         line.push_back(read);

 43         read.x = a; read.sign = -1;

 44         line.push_back(read);

 45         bool flag1 = 0, flag2 = 0; int l = Y.size();

 46         for(int j = 0; j < l; j++) {

 47             if(Y[j] == y) flag1 = 0;

 48             if(Y[j] == b) flag2 = 0;

 49          }

 50          if(!flag1) Y.push_back(y);

 51          if(!flag2) Y.push_back(b);

 52     }

 53     sort(line.begin(), line.end());

 54     sort(Y.begin(), Y.end());

 55 }

 56 

 57 void build(int l, int r, int rt)

 58 {

 59     sgt[rt].cover = 0;

 60     sgt[rt].len = 0;

 61     if(l == r) {

 62         sgt[rt].len = Y[l] - Y[l-1];

 63         return;

 64     }

 65     int m = (l + r)>>1;

 66     build(lson);

 67     build(rson);

 68 }

 69 void insert(int l, int r, int rt, int L, int R, int sign)

 70 {

 71     if(l == r) {

 72         sgt[rt].cover += sign;

 73         return;

 74     }

 75     sgt[rt].len = 0;

 76     int m = (l+r)>>1;

 77     if(L <= m)  insert(lson, L, R, sign);

 78     if(m < R)  insert(rson, L, R, sign);

 79 }

 80 double getSum(int l, int r, int rt)

 81 {

 82     if(l == r) {

 83         if(sgt[rt].cover > 0) return sgt[rt].len;

 84         return 0;

 85     }

 86     int m = (l + r)>>1;

 87     double a, b, ans;

 88     ans = getSum(lson);

 89     ans += getSum(rson);

 90     return ans;

 91 }

 92 struct node

 93 {

 94     int st, nd;

 95 };

 96 node getNum(double y1, double y2)

 97 {

 98     int l = Y.size();

 99     node res;

100     for(int i = 0; i < l; i++) {

101         if(Y[i] == y1) res.st = i+1;

102         if(Y[i] == y2) res.nd = i;

103     }

104     return res;

105 }

106 void work(int cas)

107 {

108     input();

109     int N = Y.size();

110     build(1, N-1, 1);

111     int l = line.size();

112     double ans = 0;

113     for(int i = 0; i < l; i++) {

114         node rec = getNum(line[i].y_down, line[i].y_up);

115         if(i == 0) insert(1, N-1, 1, rec.st, rec.nd, line[i].sign );

116         if(i == 0) continue;

117         double length = line[i].x - line[i-1].x;

118         ans += length*getSum(1, N-1, 1);

119         insert(1, N-1, 1, rec.st, rec.nd, line[i].sign );

120     }

121     printf("Test case #%d\nTotal explored area: %0.2f\n\n", cas, ans);

122 }

123 int main()

124 {

125     int cnt = 0;

126     while(1) {

127         scanf("%d", &n); if(n == 0) break;

128         work(++cnt);

129     }

130     return 0;

131 }

View Code