125 lines
2.8 KiB
C++
125 lines
2.8 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cmath>
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#include <cstring>
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using namespace std;
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const double inf = 1e100, EPS = 1e-6;
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const int W = 20;
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double l, now;
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int n;
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//一道墙
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struct wall
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{
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double x, y[6], val[5];
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} w[W];
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// big bug:double->int
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double length(double x1, double y1, double x2, double y2)
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{
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double x = x1 - x2, y = y1 - y2;
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return sqrt(x * x + y * y);
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}
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double cross(double x1, double y1, double x2, double y2)
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{
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return x1 * y2 - x2 * y1;
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}
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double same(double x0, double y0, double x3, double y3, double x1, double y1, double x2, double y2)
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{
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double x = x3 - x0, y = y3 - y0; // y0->x0
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return cross(x, y, x1 - x0, y1 - y0) * cross(x, y, x2 - x0, y2 - y0);
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}
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// WA double 判断正负要用
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int sign(double d)
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{
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if (fabs(d) < EPS)
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{
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return 0;
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}
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else
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return d > 0 ? 1 : -1;
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}
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bool ob(int li, int lj, int ri, int rj)
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{
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for (int i = li + 1; i < ri; i++)
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{
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for (int j = 0; j <= 4; j += 2)
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{
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// printf("(%.0lf,%.0lf)(%.0lf,%.0lf)/(%.0lf,%.0lf)(%.0lf,%.0lf):",w[i].x,w[i].y[j],w[i].x,w[i].y[j+1],w[li].x,w[li].y[lj],w[ri].x,w[ri].y[rj]);
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// printf("[%.2lf/%.2lf]\n",same(w[i].x,w[i].y[j],w[i].x,w[i].y[j+1],w[li].x,w[li].y[lj],w[ri].x,w[ri].y[rj]),same(w[li].x,w[li].y[lj],w[ri].x,w[ri].y[rj],w[i].x,w[i].y[j],w[i].x,w[i].y[j+1]));
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//两个都同方向才是，应该&&，错以为|| ,不是0都是真 两个小于0才是香蕉
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if (sign(same(w[i].x, w[i].y[j], w[i].x, w[i].y[j + 1], w[li].x, w[li].y[lj], w[ri].x, w[ri].y[rj])) < 0 && sign(same(w[li].x, w[li].y[lj], w[ri].x, w[ri].y[rj], w[i].x, w[i].y[j], w[i].x, w[i].y[j + 1])) < 0)
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{
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return 0;
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}
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}
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}
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return 1;
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}
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void find(int ii, int jj)
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{
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for (int i = 0; i < ii; i++)
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{
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for (int j = 1; j <= 4; j++)
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{
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l = length(w[ii].x, w[ii].y[jj], w[i].x, w[i].y[j]);
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now = w[i].val[j] + l; // i j ii,jj搞反了
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if (now < w[ii].val[jj] && ob(i, j, ii, jj))
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{
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w[ii].val[jj] = now;
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}
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// printf("(%.0lf,%.0lf)(%.0lf,%.0lf):length:%.3lf,now:%.3lf，val:%.3lf\n",w[ii].x,w[ii].y[jj],w[i].x,w[i].y[j],l,now,w[ii].val[jj]);
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if (i == 0)
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break;
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}
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}
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}
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void doit()
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{
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for (int i = 1; i <= n; i++)
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{
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for (int j = 1; j <= 4; j++)
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{
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find(i, j);
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if (i == n)
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break;
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}
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}
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}
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int main()
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{
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while (1)
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{
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scanf("%d", &n);
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if (n == -1)// 结束
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return 0;
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memset(&w, 0, sizeof(wall) * (n + 1));
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w[0].x = 0;
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w[0].y[1] = 5;
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w[0].val[1] = 0;
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for (int i = 1; i <= n; i++)
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{
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w[i].y[0] = 0;
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w[i].y[5] = 10;
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for (int j = 1; j <= 4; j++) //又打成i
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{
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w[i].val[j] = inf;
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}
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}
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for (int i = 1; i <= n; i++)
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{
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scanf("%lf", &w[i].x);
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// cin>>w[i].x;
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for (int j = 1; j <= 4; j++) // 又是j
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{
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scanf("%lf", &w[i].y[j]);
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// cin>>w[i].y[j];
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}
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}
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w[++n].x = 10;
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w[n].y[1] = 5;
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w[n].val[1] = inf; // bug 没赋值
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doit();
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printf("%.2lf\n", w[n].val[1]);
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}
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return 0;
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}
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