ACM-ICPC Asia Training League 暑假第一阶段第五场 BCDI
B 求两个点到圆的切点的距离加上两个切点的弧长
1 #include <bits/stdc++.h> 2 #define ll long long 3 using namespace std; 4 const int N = 1e5+10; 5 double x,y,gx,gy,xa,xb,xc,ya,yb,yc; 6 double ans1[4], ans2[4]; 7 double dis(double x1, double y1, double x2, double y2) { 8 return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)); 9 } 10 11 int main() { 12 double x, y, gx, gy, x1, y1, r1, x2, y2, r2; 13 cin >> x >> y >> gx >> gy >> x1 >> y1 >> r1 >> x2 >> y2 >> r2; 14 double xx1 = dis(x,y,x2,y2); 15 double xx2 = dis(gx,gy,x2,y2); 16 double ans1 = sqrt(xx1*xx1-r2*r2); 17 double ans2 = sqrt(xx2*xx2-r2*r2); 18 double xx3 = dis(x,y,gx,gy); 19 double a1 = acos(r2/xx1); 20 double a2 = acos(r2/xx2); 21 double a3 = acos((xx1*xx1+xx2*xx2-xx3*xx3)/(2*xx1*xx2)); 22 double ans3 = (a3-a2-a1)*r2; 23 printf("%.10f\n",ans1+ans2+ans3); 24 return 0; 25 }
C 滑雪问题，m条路径，从高处往地处滑，求能滑的最长路径是多少，从低往高处求，dfs可以过。
1 #include <bits/stdc++.h> 2 #define ll long long 3 using namespace std; 4 const int N = 1e3+10; 5 typedef pair<int,int> P; 6 vector<P> vs[N]; 7 int d[N]; 8 void dfs(int v) { 9 for(auto p : vs[v]) { 10 int u = p.first, w = p.second; 11 if(d[u] < d[v] + w) { 12 d[u] = d[v] + w; 13 dfs(u); 14 } 15 } 16 } 17 int main() { 18 int n, m; 19 cin >> n >> m; 20 for(int i = 0; i < m; i ++) { 21 int u, v, w; 22 cin >> u >> v >> w; 23 vs[v].push_back(P(u,w)); 24 } 25 for(int i = 1; i <= n; i ++) { 26 dfs(i); 27 } 28 int MAX = 0; 29 for(int i = 1; i <= n; i ++) MAX = max(MAX, d[i]); 30 printf("%d\n",MAX); 31 return 0; 32 }
D n个数，求有多少中由n+1个数组成的
1 #include <bits/stdc++.h> 2 #define INF 0x3f3f3f3f 3 using namespace std; 4 int n, x, MIN1 = INF, MIN2 = -INF; 5 int main() { 6 cin >> n; 7 int tmp = 0; 8 for(int i = 1; i <= n; i ++) { 9 cin >> x; 10 tmp = x - tmp; 11 if(i&1) MIN1 = min(MIN1, tmp); 12 else MIN2 = max(MIN2,-tmp); 13 } 14 if(MIN2>MIN1) printf("0\n"); 15 else if(MIN2 < 0 && MIN1 < 0) printf("0\n"); 16 else if(MIN2 < 0 && MIN1 >= 0) printf("%d\n",MIN1+1); 17 else printf("%d\n",MIN1-MIN2+1); 18 return 0; 19 }
I 前面的等级大于后面的，只要前面的赢了后面的就一点赢，全部平均也算英雄赢。
1 #include <bits/stdc++.h> 2 #define ll long long 3 using namespace std; 4 const int N = 1e5+10; 5 int n; 6 int a[N], b[N]; 7 int main() { 8 int x; 9 cin >> n; 10 for(int i = 0; i < n; i ++) cin >> a[i]; 11 for(int i = 0; i < n; i ++) cin >> b[i]; 12 int id = b[0] - a[0]; 13 if(id < 0) return 0*printf("0\n"); 14 for(int i = 1; i < n; i ++) { 15 if(b[i] - a[i] > id) { 16 return 0*printf("%d\n",id+1); 17 } else if(b[i] - a[i] < id) { 18 return 0*printf("%d\n",id); 19 } 20 } 21 printf("%d\n",id); 22 return 0; 23 }
