好久没打过abc了。
题目链接：https://atcoder.jp/contests/abc137/tasks_print
A：
水题。
1 /* basic header */ 2 #include <bits/stdc++.h> 3 /* define */ 4 #define ll long long 5 #define dou double 6 #define pb emplace_back 7 #define mp make_pair 8 #define sot(a,b) sort(a+1,a+1+b) 9 #define rep1(i,a,b) for(int i=a;i<=b;++i) 10 #define rep0(i,a,b) for(int i=a;i<b;++i) 11 #define eps 1e-8 12 #define int_inf 0x3f3f3f3f 13 #define ll_inf 0x7f7f7f7f7f7f7f7f 14 #define lson (curpos<<1) 15 #define rson (curpos<<1|1) 16 /* namespace */ 17 using namespace std; 18 /* header end */ 19 20 int a, b; 21 22 int main() { 23 cin >> a >> b; 24 cout << max(max(a + b, a - b), a * b) << endl; 25 return 0; 26 }
B：
一开始还看错题了。
1 /* basic header */ 2 #include <bits/stdc++.h> 3 /* define */ 4 #define ll long long 5 #define dou double 6 #define pb emplace_back 7 #define mp make_pair 8 #define sot(a,b) sort(a+1,a+1+b) 9 #define rep1(i,a,b) for(int i=a;i<=b;++i) 10 #define rep0(i,a,b) for(int i=a;i<b;++i) 11 #define eps 1e-8 12 #define int_inf 0x3f3f3f3f 13 #define ll_inf 0x7f7f7f7f7f7f7f7f 14 #define lson (curpos<<1) 15 #define rson (curpos<<1|1) 16 /* namespace */ 17 using namespace std; 18 /* header end */ 19 20 const int lim = 1e6; 21 int k, x; 22 23 int main() { 24 cin >> k >> x; 25 for (int i = x - k + 1; i <= x + k - 1; i++) { 26 if (i < -lim || i > lim) continue; 27 cout << i << " "; 28 } 29 puts(""); 30 return 0; 31 }
C：
所有字符串自身sort一遍后再sort一遍，对于重复的字符串，ans+=C(重复个数,2)。
1 /* basic header */ 2 #include <bits/stdc++.h> 3 /* define */ 4 #define ll long long 5 #define dou double 6 #define pb emplace_back 7 #define mp make_pair 8 #define sot(a,b) sort(a+1,a+1+b) 9 #define rep1(i,a,b) for(int i=a;i<=b;++i) 10 #define rep0(i,a,b) for(int i=a;i<b;++i) 11 #define eps 1e-8 12 #define int_inf 0x3f3f3f3f 13 #define ll_inf 0x7f7f7f7f7f7f7f7f 14 #define lson (curpos<<1) 15 #define rson (curpos<<1|1) 16 /* namespace */ 17 using namespace std; 18 /* header end */ 19 20 const int maxn = 1e5 + 10; 21 int n; 22 string s[maxn]; 23 ll ans = 0; 24 25 int main() { 26 scanf("%d", &n); 27 rep1(i, 1, n) { 28 cin >> s[i]; 29 sort(s[i].begin(), s[i].end()); 30 } 31 sort(s + 1, s + 1 + n); 32 int cnt = 1; 33 rep1(i, 2, n) { 34 if (s[i] == s[i - 1]) cnt++; 35 else { 36 ans += (ll)cnt * (cnt - 1) / 2; 37 cnt = 1; 38 } 39 } 40 ans += (ll)cnt * (cnt - 1) / 2; 41 printf("%lld ", ans); 42 return 0; 43 }
D：
正向思考非常麻烦，不妨倒着枚举还剩多少天。用一个优先队列维护可做工作的最大收益即可。
1 /* basic header */ 2 #include <bits/stdc++.h> 3 /* define */ 4 #define ll long long 5 #define dou double 6 #define pb emplace_back 7 #define mp make_pair 8 #define sot(a,b) sort(a+1,a+1+b) 9 #define rep1(i,a,b) for(int i=a;i<=b;++i) 10 #define rep0(i,a,b) for(int i=a;i<b;++i) 11 #define eps 1e-8 12 #define int_inf 0x3f3f3f3f 13 #define ll_inf 0x7f7f7f7f7f7f7f7f 14 #define lson (curpos<<1) 15 #define rson (curpos<<1|1) 16 /* namespace */ 17 using namespace std; 18 /* header end */ 19 20 const int maxn = 1e5 + 10; 21 // const int maxn = 5; 22 struct Job { 23 int earn, wait; 24 bool operator<(const Job &rhs)const { 25 if (wait != rhs.wait) return wait < rhs.wait; 26 else return earn > rhs.earn; 27 } 28 } a[maxn]; 29 int n, m, tot = 0, p = 0; 30 ll ans = 0; 31 32 int main() { 33 scanf("%d%d", &n, &m); 34 rep1(i, 1, n) { 35 int earn, wait; scanf("%d%d", &wait, &earn); 36 if (wait > m) continue; 37 a[++tot].wait = wait; a[tot].earn = earn; 38 } 39 int p = 0; 40 sort(a + 1, a + 1 + tot); 41 priority_queue<int>q; 42 while (!q.empty()) q.pop(); 43 for (int reDay = 1; reDay <= m && p <= tot; reDay++) { 44 while (p < tot && a[p + 1].wait <= reDay) { 45 p++; q.push(a[p].earn); 46 } 47 if (!q.empty()) ans += (ll)q.top(); 48 if (!q.empty()) q.pop(); 49 } 50 printf("%lld ", ans); 51 return 0; 52 }
E：
Bellmen-ford最短路。
F：
1 /* basic header */ 2 #include <bits/stdc++.h> 3 /* define */ 4 #define ll long long 5 #define dou double 6 #define pb emplace_back 7 #define mp make_pair 8 #define sot(a,b) sort(a+1,a+1+b) 9 #define rep1(i,a,b) for(int i=a;i<=b;++i) 10 #define rep0(i,a,b) for(int i=a;i<b;++i) 11 #define eps 1e-8 12 #define int_inf 0x3f3f3f3f 13 #define ll_inf 0x7f7f7f7f7f7f7f7f 14 #define lson (curpos<<1) 15 #define rson (curpos<<1|1) 16 /* namespace */ 17 using namespace std; 18 /* header end */ 19 20 struct CombineSmall { 21 int m; 22 vector<vector<int>> F; 23 CombineSmall(int n, int m): m(m), F(n) { 24 for (int i = 1; i < n; i++) F[i].resize(i + 1); 25 } 26 int com(int n, int k) { 27 return !k ? 1 : k > n ? 0 : k + k > n ? com(n, n - k) : F.at(n)[k] ? F[n][k] : F[n][k] = (com(n - 1, k) + com(n - 1, k - 1)) % m; 28 } 29 }; 30 31 int main() { 32 int p; scanf("%d", &p); 33 vector<int>b(p); 34 CombineSmall cb(p, p); 35 for (int i = 0; i < p; i++) { 36 int ai; scanf("%d", &ai); 37 if (!ai) continue; 38 vector<int> pa(p); pa[0] = 1; 39 for (int j = 1; j < p; j++) pa[j] = (ll)pa[j - 1] * i % p; 40 b[0] = (b[0] + 1) % p; 41 for (int j = 0; j < p; j++) { 42 int cof = (ll)cb.com(p - 1, j) * pa[p - 1 - j] % p; 43 if (~(p - 1 - j) & 1) cof = p - cof; 44 b[j] = (b[j] + cof) % p; 45 } 46 } 47 for (int i = 0; i < p; i++) printf("%d%c", b[i], i == p - 1 ? ' ' : ' '); 48 return 0; 49 }