地址http://acm.hust.edu.cn/vjudge/contest/view.action?cid=72728#overview
A：简单贪心
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define INF 0x3f3f3f3f 16 #define inf (-((LL)1<<40)) 17 #define lson k<<1, L, mid 18 #define rson k<<1|1, mid+1, R 19 #define mem0(a) memset(a,0,sizeof(a)) 20 #define mem1(a) memset(a,-1,sizeof(a)) 21 #define mem(a, b) memset(a, b, sizeof(a)) 22 #define FIN freopen("in.txt", "r", stdin) 23 #define FOUT freopen("out.txt", "w", stdout) 24 #define rep(i, a, b) for(int i = a; i <= b; i ++) 25 26 template<class T> T CMP_MIN(T a, T b) { return a < b; } 27 template<class T> T CMP_MAX(T a, T b) { return a > b; } 28 template<class T> T MAX(T a, T b) { return a > b ? a : b; } 29 template<class T> T MIN(T a, T b) { return a < b ? a : b; } 30 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; } 31 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b; } 32 33 //typedef __int64 LL; 34 typedef long long LL; 35 const int MAXN = 1010; 36 const int MAXM = 2000010; 37 const double eps = 1e-4; 38 39 int n, a[110000]; 40 41 int main() 42 { 43 while(~scanf("%d", &n)) { 44 rep (i, 0, n - 1) scanf("%d", &a[i]); 45 sort(a, a + n); 46 int ans = 0; 47 rep (i, 0, n - 1) ans = max(ans, a[i] + n + 1 - i); 48 cout << ans << endl; 49 } 50 return 0; 51 }
B:不会= =
C:YY一下，将需要计算的值写成a * 10 ^ p + b（这里可以看到b < 10^p 且 1<=a<=9）,那么可以写出等式：
（a * 10 ^ p + b） * X = b * 10 + a 移项后可以得到：
（X * 10^p - 1） * a = (10 - X) * b
由于X * 10^p - 1一定是整数，所以若X>=10一定是No solution，然后便是枚举a=[1, 9], p=[0,7]算出所有的b，若算出来b是整数，便记录答案即可
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define INF 0x3f3f3f3f 16 #define inf (-((LL)1<<40)) 17 #define lson k<<1, L, mid 18 #define rson k<<1|1, mid+1, R 19 #define mem0(a) memset(a,0,sizeof(a)) 20 #define mem1(a) memset(a,-1,sizeof(a)) 21 #define mem(a, b) memset(a, b, sizeof(a)) 22 #define FIN freopen("in.txt", "r", stdin) 23 #define FOUT freopen("out.txt", "w", stdout) 24 #define rep(i, a, b) for(int i = a; i <= b; i ++) 25 26 template<class T> T CMP_MIN(T a, T b) { return a < b; } 27 template<class T> T CMP_MAX(T a, T b) { return a > b; } 28 template<class T> T MAX(T a, T b) { return a > b ? a : b; } 29 template<class T> T MIN(T a, T b) { return a < b ? a : b; } 30 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; } 31 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b; } 32 33 //typedef __int64 LL; 34 typedef long long LL; 35 const int MAXN = 1010; 36 const int MAXM = 2000010; 37 const double eps = 1e-6; 38 39 double x; 40 LL a, p; 41 LL ans[10000]; 42 43 int main() 44 { 45 while(~scanf("%lf", &x)) { 46 if(x >= 10) {puts("No solution");continue;} 47 int cnt = 0; 48 for(a = 1; a <=9; a ++) { 49 for(p = 0; p <= 7; p ++) { 50 double b = a * (x * pow(10, p) - 1) / (10.0 - x); 51 if(fabs(b - (LL)(b + eps)) < eps && b < pow(10, p)) ans[cnt++] = (LL)(a * pow(10, p) + b); 52 } 53 } 54 sort(ans, ans + cnt); 55 rep (i, 0, cnt - 1) cout << ans[i] << endl; 56 if(cnt == 0) puts("No solution"); 57 } 58 return 0; 59 }
D:给n个点，求最远点距
我的方法后来被我自己证明是错的了，，，，算了 还是把代码贴上来，毕竟A了
我是用的凸包+三分求极值（实际不可以求极值来算= =）
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define eps 1e-12 16 #define MAXN 55 17 #define INF 1e30 18 #define mem0(a) memset(a,0, sizeof(a)) 19 #define mem1(a) memset(a,-1,sizeof(a)) 20 #define rep(i, a, b) for(int i = a; i <= b; i ++) 21 double MAX(double a, double b) {return a > b ? a : b;} 22 double MIn(double a, double b) {return a < b ? a : b;} 23 typedef long long LL; 24 /****************************************计算几何头文件**************************************************/ 25 struct Point{ 26 int x,y; 27 Point(int x=0, int y=0):x(x),y(y){} 28 bool operator < (const Point &A) const { 29 return x != A.x ? x < A.x : y < A.y; 30 } 31 }; 32 33 Point operator + (Point A, Point B) {return Point(A.x+B.x, A.y+B.y);} 34 35 Point operator - (Point A, Point B) {return Point(A.x-B.x, A.y-B.y);} 36 37 double Dot(Point A, Point B) { return A.x*B.x + A.y*B.y;} //点积 38 39 double Length(Point A) { return sqrt(Dot(A,A));} //向量长度 40 41 double Angle(Point A, Point B) {return acos(Dot(A,B) / Length(A) / Length(B));}//向量夹角 42 43 double cross(Point A, Point B) {return A.x*B.y - A.y*B.x;} 44 45 bool crossed(Point a, Point b, Point c, Point d)//线段ab和cd是否相交 46 { 47 if(cross(a-c, d-c)*cross(b-c, d-c)<=0 48 && cross(c-a, b-a)*cross(d-a, b-a)<=0) 49 { 50 return true; 51 } 52 return false; 53 } 54 55 int convexHull(Point* p, int n, Point* ch) 56 { 57 sort(p, p + n); 58 int m = 0; 59 for(int i = 0; i < n; i ++) { 60 while(m > 1 && cross(ch[m-1]-ch[m-2], p[i]-ch[m-2]) <= 0) m--; 61 ch[m++] =p[i]; 62 } 63 int k = m; 64 for(int i = n - 2; i >= 0; i --) { 65 while(m > k && cross(ch[m-1]-ch[m-2], p[i]-ch[m-2]) <= 0) m--; 66 ch[m++] = p[i]; 67 } 68 if(n > 1) m --; 69 return m; 70 } 71 72 /****************************************************************************************************/ 73 Point p[110000], q[210000]; 74 int n, m; 75 76 double dis(Point a, Point b) 77 { 78 double x = (double)a.x - b.x, y = (double)a.y - b.y; 79 return sqrt(x * x + y * y); 80 } 81 82 double tsearch(int id, int low, int high) 83 { 84 while(low + 2 < high) { 85 int ml = low + (high - low) / 3; 86 int mr = (high + ml) >> 1; 87 if(dis(q[ml], q[id]) > dis(q[mr], q[id])) { 88 high = mr; 89 } 90 else low = ml; 91 } 92 return max(dis(q[low], q[id]), max(dis(q[low + 1], q[id]), dis(q[high], q[id]))); 93 } 94 95 int main() 96 { 97 while(~scanf("%d", &n)) { 98 rep (i, 0, n - 1) { 99 scanf("%d %d", &p[i].x, &p[i].y); 100 } 101 m = convexHull(p, n, q); 102 double ans = 0; 103 rep (i, 0, m- 1) q[i + m] = q[i]; 104 rep (i, 0, m - 1) { 105 ans = max(ans, tsearch(i, i + 1, i + m)); 106 } 107 printf("%.8lf ", ans); 108 } 109 return 0; 110 }
E:一道细节题
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define INF 0x3f3f3f3f 16 #define inf (-((LL)1<<40)) 17 #define lson k<<1, L, mid 18 #define rson k<<1|1, mid+1, R 19 #define mem0(a) memset(a,0,sizeof(a)) 20 #define mem1(a) memset(a,-1,sizeof(a)) 21 #define mem(a, b) memset(a, b, sizeof(a)) 22 #define FIN freopen("in.txt", "r", stdin) 23 #define FOUT freopen("out.txt", "w", stdout) 24 #define rep(i, a, b) for(int i = a; i <= b; i ++) 25 26 template<class T> T CMP_MIN(T a, T b) { return a < b; } 27 template<class T> T CMP_MAX(T a, T b) { return a > b; } 28 template<class T> T MAX(T a, T b) { return a > b ? a : b; } 29 template<class T> T MIN(T a, T b) { return a < b ? a : b; } 30 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; } 31 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b; } 32 33 //typedef __int64 LL; 34 typedef long long LL; 35 const int MAXN = 1010; 36 const int MAXM = 2000010; 37 const double eps = 1e-4; 38 39 char s[110000], t[110000]; 40 41 int main() 42 { 43 //FIN; 44 while(gets(s)) { 45 gets(t); 46 int f = 0, r = strlen(t) - 1; 47 int l1 = strlen(s), l2 = strlen(t); 48 for (f = 0; s[f] && t[f] && s[f] == t[f];f ++); 49 for (;l1 - (l2 - r) >= 0 && r >= 0 && s[l1 - (l2 - r)] == t[r]; r--); 50 if(r >= f) { 51 if(f == l1 || l1 + r - l2 < 0) cout << l2 - l1 << endl; 52 else cout << r - f + 1 << endl; 53 } 54 else { 55 if(l2 <= l1) cout << 0 << endl; 56 else cout << min(r + 1, l2 - f) << endl; 57 } 58 } 59 return 0; 60 }
F:模拟暴力
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define INF 0x3f3f3f3f 16 #define inf (-((LL)1<<40)) 17 #define lson k<<1, L, mid 18 #define rson k<<1|1, mid+1, R 19 #define mem0(a) memset(a,0,sizeof(a)) 20 #define mem1(a) memset(a,-1,sizeof(a)) 21 #define mem(a, b) memset(a, b, sizeof(a)) 22 #define FIN freopen("in.txt", "r", stdin) 23 #define FOUT freopen("out.txt", "w", stdout) 24 #define rep(i, a, b) for(int i = a; i <= b; i ++) 25 26 template<class T> T CMP_MIN(T a, T b) { return a < b; } 27 template<class T> T CMP_MAX(T a, T b) { return a > b; } 28 template<class T> T MAX(T a, T b) { return a > b ? a : b; } 29 template<class T> T MIN(T a, T b) { return a < b ? a : b; } 30 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; } 31 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b; } 32 33 //typedef __int64 LL; 34 typedef long long LL; 35 const int MAXN = 1010; 36 const int MAXM = 2000010; 37 const double eps = 1e-6; 38 39 char num[10][20] = { 40 "**** ** ** ****", 41 " * * * * *", 42 "*** ***** ***", 43 "*** **** ****", 44 "* ** **** * *", 45 "**** *** ****", 46 "**** **** ****", 47 "*** * * * *", 48 "**** ***** ****", 49 "**** **** ****" 50 }; 51 52 char ma[100][110]; 53 54 int trans(int y) 55 { 56 char s[20] = {0}; 57 for(int i = 0; i < 5; i ++) { 58 for(int j = 0; j < 3; j ++) { 59 s[i*3+j] = ma[i][y + j]; 60 if(s[i*3+j]==0) s[i*3+j]=' '; 61 } 62 } 63 for(int i = 0; i < 10; i ++) if(strcmp(num[i], s) == 0) 64 return i; 65 return -1; 66 } 67 68 int main() 69 { 70 while(gets(ma[0])) { 71 for(int i = 1; i < 5;i ++) { 72 gets(ma[i]); 73 } 74 int num = 0, l = strlen(ma[0]); 75 for(int y = 0; y < l- 2; y += 4) { 76 num = num * 10 + trans(y); 77 } 78 if(num % 6 == 0) puts("BEER!!"); 79 else puts("BOOM!!"); 80 } 81 return 0; 82 }
G：关键是看懂提：
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define INF 0x3f3f3f3f 16 #define inf (-((LL)1<<40)) 17 #define lson k<<1, L, mid 18 #define rson k<<1|1, mid+1, R 19 #define mem0(a) memset(a,0,sizeof(a)) 20 #define mem1(a) memset(a,-1,sizeof(a)) 21 #define mem(a, b) memset(a, b, sizeof(a)) 22 #define FIN freopen("in.txt", "r", stdin) 23 #define FOUT freopen("out.txt", "w", stdout) 24 #define rep(i, a, b) for(int i = a; i <= b; i ++) 25 26 template<class T> T CMP_MIN(T a, T b) { return a < b; } 27 template<class T> T CMP_MAX(T a, T b) { return a > b; } 28 template<class T> T MAX(T a, T b) { return a > b ? a : b; } 29 template<class T> T MIN(T a, T b) { return a < b ? a : b; } 30 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; } 31 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b; } 32 33 //typedef __int64 LL; 34 typedef long long LL; 35 const int MAXN = 1010; 36 const int MAXM = 2000010; 37 const double eps = 1e-4; 38 39 char s[110000], t[110000]; 40 int n; 41 42 int main() 43 { 44 while(~scanf("%d%*c", &n)) { 45 gets(s); gets(t); 46 int l1 = strlen(s), l2 = strlen(t), num = 0; 47 if(strcmp(s, t) == 0 && n % 2 == 0) { 48 puts("Deletion succeeded"); 49 continue; 50 } 51 for(int i = 0; i < l1 ; i ++) if(s[i] != t[i]) num++; 52 printf("%s ", (num==l1&&(n&1)) ? "Deletion succeeded" : "Deletion failed"); 53 } 54 return 0; 55 }
H:不敢看( ⊙ o ⊙ )啊！