#7：怀念儿时的春节——9

 1 #include <bits/stdc++.h>
 2 #define ll long long
 3 using namespace std;
 4 
 5 struct point {
 6     ll x, y;
 7     int id;
 8     bool operator < (const point b) const {
 9         if (x != b.x)    return x < b.x;
10         return y < b.y;
11     }
12 }c[100005];
13 
14 bool ok(int i, int j, int k) {
15     return (c[k].y-c[j].y)*(c[j].x-c[i].x) != (c[j].y-c[i].y)*(c[k].x-c[j].x);
16 }
17 
18 int main() {
19     int n;
20     cin >> n;
21     for (int i = 1; i <= n; i++) {
22         cin >> c[i].x >> c[i].y;
23         c[i].id = i;
24     }
25     sort(c+1, c+1+n);
26     for (int j = 3; j <= n; j++) {
27         if (ok(1, 2, j)) {
28             printf("%d %d %d\n", c[1].id, c[2].id, c[j].id);
29             return 0;
30         }
31     }
32 }

 1 #include <bits/stdc++.h>
 2 #define ld long double
 3 #define maxn 100005
 4 using namespace std;
 5 
 6 int n, p;
 7 ld pro[maxn];
 8 ld ans;
 9 
10 int main() {
11     cin >> n >> p;
12     for (int i = 1; i <= n; i++) {
13         int l, r;
14         cin >> l >> r;
15         ld cnt = r/p - (l-1)/p;
16         ld range = r-l+1;
17         pro[i] = 1.0 - cnt/range;
18     }
19     
20     for (int i = 1; i <= n; i++) {
21         int nxt = i == n ? 1 : i+1;
22         ans += 1.0 - pro[i]*pro[nxt];
23     }
24     cout << fixed << setprecision(6) << ans*2000;
25     return 0;
26 }

 1 #include <cstdio>
 2 #define db double
 3 int n, s;
 4 db dp[1005][1005];
 5 
 6 int main() {
 7     scanf("%d%d", &n, &s);
 8     for (int i = n; ~i; i--)
 9         for (int j = s; ~j; j--) {
10             if (i == n && j == s)    continue;
11             db p1 = (db)(n-i) * (s-j) / n / s;
12             db p2 = (db)i * (s-j) / n / s;
13             db p3 = (db)(n-i) * j / n / s;
14             db p4 = (db)i * j / n / s;
15             dp[i][j] = (p1*dp[i+1][j+1] + p2*dp[i][j+1] + p3*dp[i+1][j] + 1) / (1-p4);
16         }
17     printf("%.4f", dp[0][0]);
18     return 0;
19 }

 1 #include <cstdio>
 2 #include <queue>
 3 #define ll long long
 4 using namespace std;
 5 
 6 int n, t;
 7 ll ans;
 8 priority_queue<ll> Q;
 9 
10 int main() {
11     scanf("%d", &n);
12     for (int i = 0; i < n; i++) {
13         ll x;
14         scanf("%lld", &x);
15         if (x & 1)  Q.push(x), t++;
16         else    ans += x;
17     }
18     for (int i = 0; i < t>>1; i++) {
19         ll x = Q.top();
20         Q.pop();
21         ll y = Q.top();
22         Q.pop();
23         ans += x + y;
24     }
25     printf("%lld", ans);
26     return 0;
27 }

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 int n, m;
 5 int du[505];
 6 bool mp[505][505];
 7 char s[505];
 8 
 9 inline void judge(int x) {
10     if (du[x] == n-1)
11         s[x] = ‘b‘;
12 }
13 
14 int main() {
15     cin >> n >> m;
16     for (int i = 0; i < m; i++) {
17         int a, b;
18         cin >> a >> b;
19         mp[a][b] = mp[b][a] = true;
20         du[a]++, du[b]++;
21         judge(a), judge(b);
22     }
23 
24     int tmp = 1;
25     for (int i = 1; i <= n; i++) {
26         mp[i][i] = true;
27         if (s[i] != ‘b‘) {
28             tmp = i;
29         }
30     }
31 
32     for (int i = 1; i <= n; i++)
33         if (!s[i]) {
34             if (mp[tmp][i])    s[i] = ‘a‘;
35             else    s[i] = ‘c‘;
36         }
37     
38     bool flag = true;
39     for (int i = 1; i <= n; i++)
40         for (int j = 1; j <= n; j++)
41             if (mp[i][j] && abs(s[i] - s[j]) == 2)
42                 flag = false;
43             else if (!mp[i][j] && abs(s[i] - s[j]) < 2)
44                 flag = false;
45 
46     if (flag) {
47         puts("Yes");
48         printf("%s", s+1);
49     } else {
50         puts("No");
51     }
52 
53     return 0;
54 }

 1 #include <bits/stdc++.h>
 2 #define ll long long
 3 #define maxn 1000005
 4 #define INF (1LL<<60)
 5 #define pb push_back
 6 #define rep(i, a, b)    for (int i = a; i <= b; i++)
 7 using namespace std;
 8 
 9 int n, a, b;
10 int val[maxn];
11 vector<int> gcd;
12 ll ans = INF;
13 
14 void get(int num) {
15     for (int i = 2; i * i <= num; i++) {
16         if (num % i == 0) {
17             gcd.pb(i);
18             while (num % i == 0)
19                 num /= i;
20         }
21     }
22     if (num > 1)    gcd.pb(num);
23 }
24 
25 ll cal(int x) {
26     ll havnt_delet = 0ll, is_deleting = 0ll, hav_done = 0ll;
27     rep(i, 1, n) {
28         if (val[i] % x == 0) {
29             hav_done = min(hav_done, is_deleting);
30             is_deleting = min(havnt_delet, is_deleting) + a;
31         }
32         else if ((val[i]-1) % x == 0 || (val[i]+1) % x == 0) {
33             hav_done = min(hav_done, is_deleting) + b;
34             is_deleting = min(havnt_delet, is_deleting) + a;
35             if (havnt_delet < INF) {
36                 havnt_delet += b;
37             }
38         } else {
39             is_deleting = min(havnt_delet, is_deleting) + a;
40             hav_done = havnt_delet = INF;
41         }
42     }
43     return min(havnt_delet, min(is_deleting, hav_done));
44 }
45 
46 int main() {
47     cin >> n >> a >> b;
48     rep(i, 1, n)    cin >> val[i];
49 
50     rep(i, -1, 1) {
51         get(val[1] + i);
52         get(val[n] + i);
53     }
54     gcd.erase(unique(gcd.begin(), gcd.end()), gcd.end());
55     for (auto i : gcd)
56         ans = min(ans, cal(i));
57 
58     cout << ans;
59     return 0;
60 }

 1 #include <bits/stdc++.h>
 2 #define maxn 20005
 3 #define pb push_back
 4 #define mp make_pair
 5 #define P pair<int, int>
 6 #define fi first
 7 #define se second
 8 using namespace std;
 9 
10 int n, m, maxx;
11 vector<P> v[maxn];
12 vector<int> tmp[maxn];
13 int vis[maxn];
14 int l, r, mid;
15 
16 bool dfs(int cur, int color) {
17     vis[cur] = color;
18     for (int i : tmp[cur])
19         if (vis[i] && vis[i] == color)
20             return false;
21         else if (!vis[i] && !dfs(i, 3-color))
22             return false;
23     return true;
24 }
25 
26 bool ok(int mid) {
27     for (int i = 1; i <= n; i++)    tmp[i].clear();
28     memset(vis, 0, sizeof(vis));
29 
30     for (int i = 1; i <= n; i++)
31         for (auto j : v[i])
32             if (j.se > mid)
33                 tmp[i].pb(j.fi);
34     for (int i = 1; i <= n; i++)    
35         if (!vis[i] && !dfs(i, 1))
36             return false;
37     return true;
38 }
39 
40 int main() {
41     cin >> n >> m;
42     for (int i = 0; i < m; i++) {
43         int a, b, c;
44         cin >> a >> b >> c;
45         v[a].pb(mp(b, c));
46         v[b].pb(mp(a, c));
47         maxx = max(maxx, c);
48     }
49     for (l = 0, r = maxx; l <= r;) {
50         mid = (l+r) >> 1;
51         if (ok(mid))    r = mid-1;
52         else    l = mid+1;
53     }
54     printf("%d", l);
55     return 0;
56 }

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 int a, b, x;
 5 vector<int> v;
 6 
 7 int main() {
 8     cin >> a >> b;
 9     for (int i = 0; i < a; i++) {
10         cin >> x;
11         v.push_back(x);
12     }
13     sort(v.begin(), v.end());
14     for (int i = 0; i < b; i++) {
15         cin >> x;
16         cout << upper_bound(v.begin(), v.end(), x) - v.begin() << " ";
17     }
18     return 0;
19 }

  1 #include <bits/stdc++.h>
  2 #define db long double
  3 using namespace std;
  4 
  5 const db PI = 3.141592653589793;
  6 const db eps = 1e-10;
  7 db da, S1, S2;
  8 
  9 struct Point {
 10     db x, y;
 11     Point(){}
 12     Point(db x, db y):x(x), y(y){}
 13 };
 14 struct Circle {
 15     Point c;
 16     db r;
 17     Circle(){}
 18     Circle(Point c, db r):c(c), r(r){}
 19     Point point(db a) {
 20         return Point(c.x + cos(a)*r, c.y + sin(a)*r);
 21     }
 22 };
 23 typedef Point Vector;
 24 int dcmp(db x) {
 25     if (x <= eps && x >= -eps)    return 0;
 26     return x > 0 ? 1 : -1;
 27 }
 28 bool operator == (Vector A, Vector B) {
 29     return dcmp(A.x - B.x) == 0 && dcmp(A.y - B.y) == 0;
 30 }
 31 Vector operator + (Vector A, Vector B) {
 32     return Vector(A.x + B.x, A.y + B.y);
 33 }
 34 Vector operator - (Vector A, Vector B) {
 35     return Vector(A.x - B.x, A.y - B.y);
 36 }
 37 Vector operator * (Vector A, db p) {
 38     return Vector(A.x * p, A.y * p);
 39 }
 40 Vector operator / (Vector A, db p) {
 41     return Vector(A.x / p, A.y / p);
 42 }
 43 db Cross(Vector A, Vector B) {
 44     return A.x * B.y - A.y * B.x;
 45 }
 46 db Dot(Vector A, Vector B) {
 47     return A.x * B.x + A.y * B.y;
 48 }
 49 db Length(Vector A) {
 50     return sqrt(Dot(A, A));
 51 }
 52 db angle(Vector A) {
 53     return atan2(A.y, A.x);
 54 }
 55 
 56 db cal(Circle C, db da) {
 57     if (da > PI/2)    da = PI - da;
 58     return C.r*C.r*da - C.r*C.r*sinl(da)*cosl(da);
 59 }
 60 
 61 int Get_Circle_Intersection(Circle C1, Circle C2, vector<Point> &v) {
 62     db d = Length(C1.c - C2.c);
 63     
 64     if (dcmp(d) == 0)    return 0;
 65     if (dcmp(C1.r + C2.r - d) < 0)    return -1;
 66     if (dcmp(fabs(C1.r-C2.r) - d) > 0)    return 0;
 67 
 68     db a = angle(C2.c - C1.c);
 69     da = acosl((C1.r*C1.r + d*d - C2.r*C2.r) / (2*C1.r*d));
 70     Point p1 = C1.point(a-da), p2 = C1.point(a+da);
 71     S1 = cal(C1, da);
 72 
 73     a = angle(C1.c - C2.c);
 74     da = acosl((C2.r*C2.r + d*d - C1.r*C1.r) / (2*C2.r*d));
 75     S2 = cal(C2, da);
 76 
 77     v.push_back(p1);
 78     if (p1 == p2)    return 1;
 79     v.push_back(p2);
 80     return 2;
 81 }
 82 
 83 bool differe(Vector A, Vector B, Vector C) {
 84     return dcmp(Cross(A, B)) * dcmp(Cross(A, C)) <= 0;
 85 }
 86 
 87 Circle C1, C2;
 88 vector<Point> v;
 89 db ans;
 90 
 91 int main() {
 92     cin >> C1.c.x >> C1.c.y >> C1.r;
 93     cin >> C2.c.x >> C2.c.y >> C2.r;
 94     int k = Get_Circle_Intersection(C1, C2, v);
 95     if (k == -1) {
 96         ans = 0.0;
 97     } else if (k == 0) {
 98         db r = min(C1.r, C2.r);
 99         ans = r*r*PI;
100     } else if (k == 1) {
101         if (Dot(v[0]-C1.c, v[0]-C2.c) > 0) {
102             db r = min(C1.r, C2.r);
103             ans = r*r*PI;
104         } else    ans = 0.0;
105     } else {
106         if (differe(v[1]-v[0], C1.c-v[0], C2.c-v[0]))
107             ans = S1 + S2;
108         else if (C1.r < C2.r)
109             ans = C1.r*C1.r*PI - S1 + S2;
110         else    ans = C2.r*C2.r*PI - S2 + S1;
111     }
112     cout << fixed << setprecision(7) << ans << endl;
113     return 0;
114 }