Comet OJ Contest #4
边开着Android Studio边打，结果电脑死机了一次……题目还蛮有趣的。
题目链接：https://cometoj.com/contest/39
A：
超级温暖人心的手速题。
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[6]; 21 22 int main() { 23 int t; 24 scanf("%d", &t); 25 while (t--) { 26 int ans = 1; 27 for (int i = 1; i <= 5; i++) a[i] = 0; 28 for (int i = 1; i <= 5; i++) { 29 int x; scanf("%d", &x); a[x]++; 30 } 31 for (int i = 1; i <= 5; i++) 32 if (a[i] > a[ans]) ans = i; 33 printf("%d\n", ans); 34 } 35 return 0; 36 }
B：
打表找规律之后发现k为奇数的时候答案就是r-l+1，k为偶数的时候答案以k+1为周期找规律。
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 t; 21 22 int main() { 23 scanf("%d", &t); 24 while (t--) { 25 ll l, r, k, L, R; 26 scanf("%lld%lld%lld", &l, &r, &k); 27 if (k % 2) { 28 printf("%lld\n", r - l + 1); 29 continue; 30 } 31 r++; 32 if (l < k) L = l; 33 else L = l % (k + 1) + l / (k + 1) * k; 34 if (r < k) R = r; 35 else R = r % (k + 1) + r / (k + 1) * k; 36 printf("%lld\n", R - L); 37 } 38 return 0; 39 }
C：
不会，搬运题解好了。
1 #include <cstdio> 2 #include <vector> 3 4 const int N = 1000 + 10; 5 6 char s[N][N]; 7 int g[N][N]; 8 9 int main() { 10 int T; 11 scanf("%d", &T); 12 for (int cas = 1; cas <= T; ++cas) { 13 int n, m, k; 14 scanf("%d%d%d", &n, &m, &k); 15 for (int i = 1; i <= n; ++i) { 16 scanf("%s", s[i] + 1); 17 } 18 for (int i = 1; i <= n; ++i) { 19 for (int j = 1; j <= m; ++j) { 20 g[i][j] = g[i - 1][j] + g[i][j - 1] - g[i - 1][j - 1] + (s[i][j] == '0'); 21 } 22 } 23 if (g[n][m] == 0) { 24 for (int i = 1; i <= k; ++i) { 25 printf("%d%c", i, " \n"[i == k]); 26 } 27 continue; 28 } 29 std::vector<int> ret; 30 for (int a = 0; a <= k && a <= n - 1; ++a) { 31 int b = k - a; 32 if (b < 0 || b > m - 1) continue; 33 if (g[n][m] % ((a + 1) * (b + 1))) continue; 34 std::vector<int> xs, ys; 35 int col_sum = g[n][m] / (b + 1); 36 int row_sum = g[n][m] / (a + 1); 37 int avg = g[n][m] / ((a + 1) * (b + 1)); 38 for (int i = 0, j = 0; i <= m; ++i) { 39 if (g[n][i] % col_sum == 0 && g[n][i] / col_sum == j) { 40 ys.push_back(i); 41 ++j; 42 } 43 } 44 if (ys.size() != b + 2) continue; 45 ys.pop_back(); ys.push_back(m); 46 for (int i = 0, j = 0; i <= n; ++i) { 47 if (g[i][m] % row_sum == 0 && g[i][m] / row_sum == j) { 48 xs.push_back(i); 49 ++j; 50 } 51 } 52 if (xs.size() != a + 2) continue; 53 xs.pop_back(); xs.push_back(n); 54 bool valid = true; 55 for (size_t i = 1; i < xs.size() && valid; ++i) { 56 for (size_t j = 1; j < ys.size() && valid; ++j) { 57 int sum = g[xs[i]][ys[j]] - g[xs[i]][ys[j - 1]] - g[xs[i - 1]][ys[j]] + g[xs[i - 1]][ys[j - 1]]; 58 valid &= (sum == avg); 59 } 60 } 61 if (valid) { 62 std::vector<int> tmp; 63 for (int i = 1; i <= a; ++i) tmp.push_back(xs[i]); 64 for (int i = 1; i <= b; ++i) tmp.push_back(ys[i] + n - 1); 65 if (ret.empty() || ret > tmp) ret = tmp; 66 } 67 } 68 if (ret.empty()) puts("Impossible"); 69 else { 70 for (int i = 0; i < k; ++i) { 71 printf("%d%c", ret[i], " \n"[i == k - 1]); 72 } 73 } 74 } 75 return 0; 76 }
D：
又是个找规律的题……code via. lzh12139
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 calc(ll x) { 21 if (x < 10) return x; 22 int a[20]; a[0] = 0; 23 while (x) a[++a[0]] = x % 10, x /= 10; 24 ll tmp = 0; 25 for (int i = a[0]; i >= 2; i--) tmp = tmp * 10 + (a[i] + a[i - 1]) % 10; 26 return calc(tmp); 27 } 28 29 ll solve(ll x) { 30 ll ret = (x + 1) / 10 * 45; 31 if (x % 10 == 9) return ret; 32 int y = calc(x / 10 * 10); 33 rep1(i, 0, x % 10) ret += (y + i) % 10; 34 return ret; 35 } 36 int main() { 37 int t; scanf("%d", &t); 38 while (t--) { 39 ll l, r; scanf("%lld%lld", &l, &r); 40 printf("%lld\n", solve(r) - solve(l - 1)); 41 } 42 }
E：
1 #include <cstdio> 2 #include <vector> 3 #include <algorithm> 4 5 int solve1(const std::vector<int> &a, const std::vector<int> &b, int e) { 6 int ca = 0, cb = 0; 7 for (auto &&x: a) ca += x == e; 8 for (auto &&x: b) cb += x == e; 9 return std::min(ca, cb); 10 } 11 12 int solve2(const std::vector<int> &a, const std::vector<int> &b, int x, int y) { 13 int say = 0, sby = 0; 14 for (auto &v: a) say += v == y; 15 for (auto &v: b) sby += v == y; 16 int ret = 0; 17 for (size_t i = 0, j = 0, cx = 0; i < a.size() && j < b.size(); ++i, ++j) { 18 while (i < a.size() && a[i] != x) { 19 say -= a[i] == y; 20 ++i; 21 } 22 while (j < b.size() && b[j] != x) { 23 sby -= b[j] == y; 24 ++j; 25 } 26 if (i < a.size() && a[i] == x && j < b.size() && b[j] == x) { 27 ++cx; 28 ret = std::max<int>(ret, cx + std::min(say, sby)); 29 } 30 } 31 return ret; 32 } 33 34 int solve(const std::vector<int> &a, const std::vector<int> &b) { 35 std::vector<int> sa1(a.size() + 1), sb1(b.size() + 1); 36 for (int i = a.size() - 1; i >= 0; --i) { 37 sa1[i] = sa1[i + 1] + (a[i] == 1); 38 } 39 for (int i = b.size() - 1; i >= 0; --i) { 40 sb1[i] = sb1[i + 1] + (b[i] == 1); 41 } 42 std::vector<int> pa0, pa2, pb0, pb2; 43 for (size_t i = 0; i < a.size(); ++i) { 44 if (a[i] == 0) pa0.push_back(i); 45 if (a[i] == 2) pa2.push_back(i); 46 } 47 for (size_t i = 0; i < b.size(); ++i) { 48 if (b[i] == 0) pb0.push_back(i); 49 if (b[i] == 2) pb2.push_back(i); 50 } 51 pa2.push_back(a.size()); 52 pb2.push_back(b.size()); 53 std::reverse(pa2.begin(), pa2.end()); 54 std::reverse(pb2.begin(), pb2.end()); 55 std::vector<int> xs; 56 for (size_t i = 0; i < pa2.size() && i < pb2.size(); ++i) { 57 xs.push_back(sa1[pa2[i]] - sb1[pb2[i]]); 58 } 59 std::sort(xs.begin(), xs.end()); 60 xs.erase(std::unique(xs.begin(), xs.end()), xs.end()); 61 62 std::vector<int> bit(xs.size(), -1e9); 63 64 auto add = [](std::vector<int> &bit, int x, int v) { 65 for (; x >= 0; x -= ~x & x + 1) { 66 bit[x] = std::max(bit[x], v); 67 } 68 }; 69 70 auto get = [](std::vector<int> &bit, int x, int r = -1e9) { 71 for (; x < bit.size(); x += ~x & x + 1) { 72 r = std::max(bit[x], r); 73 } 74 return r; 75 }; 76 77 int ret = 0; 78 for (int i = std::min(pa0.size(), pb0.size()) - 1, j = 0; i >= 0; --i) { 79 while (j < pa2.size() && j < pb2.size() && pa2[j] > pa0[i] && pb2[j] > pb0[i]) { 80 int p = std::lower_bound(xs.begin(), xs.end(), sa1[pa2[j]] - sb1[pb2[j]]) - xs.begin(); 81 add(bit, p, j - sa1[pa2[j]]); 82 ++j; 83 } 84 auto p = std::lower_bound(xs.begin(), xs.end(), sa1[pa0[i]] - sb1[pb0[i]]) - xs.begin(); 85 ret = std::max(ret, sa1[pa0[i]] + get(bit, p) + i + 1); 86 } 87 return ret; 88 } 89 90 int main() { 91 int T; 92 scanf("%d", &T); 93 for (int cas = 1; cas <= T; ++cas) { 94 int n, m; 95 scanf("%d%d", &n, &m); 96 std::vector<int> a(n), b(m); 97 for (int i = 0; i < n; ++i) { 98 scanf("%d", &a[i]); 99 --a[i]; 100 } 101 for (int i = 0; i < m; ++i) { 102 scanf("%d", &b[i]); 103 --b[i]; 104 } 105 int res = std::max(std::max(solve1(a, b, 0), solve1(a, b, 1)), solve1(a, b, 2)); 106 res = std::max(res, solve2(a, b, 0, 1)); 107 res = std::max(res, solve2(a, b, 0, 2)); 108 res = std::max(res, solve2(a, b, 1, 2)); 109 res = std::max(res, solve(a, b)); 110 res = std::max(res, solve(b, a)); 111 printf("%d\n", res); 112 } 113 return 0; 114 }
F：
1 #include <cstdio> 2 #include <cassert> 3 #include <vector> 4 #include <map> 5 #include <algorithm> 6 7 using int64 = long long; 8 using uint64 = unsigned long long; 9 10 const int mod = 1e9 + 7; 11 const int N = 100; 12 13 std::vector<std::pair<uint64, uint64>> count[N]; 14 15 inline uint64 rev(uint64 ns) { 16 ns = ((ns & 0xaaaaaaaaaaaaaaaaull) >> 1) | ((ns & 0x5555555555555555ull) << 1); 17 ns = ((ns & 0xccccccccccccccccull) >> 2) | ((ns & 0x3333333333333333ull) << 2); 18 ns = ((ns & 0xf0f0f0f0f0f0f0f0ull) >> 4) | ((ns & 0x0f0f0f0f0f0f0f0full) << 4); 19 ns = ((ns & 0xff00ff00ff00ff00ull) >> 8) | ((ns & 0x00ff00ff00ff00ffull) << 8); 20 ns = ((ns & 0xffff0000ffff0000ull) >> 16) | ((ns & 0x0000ffff0000ffffull) << 16); 21 ns = ((ns & 0xffffffff00000000ull) >> 32) | ((ns & 0x00000000ffffffffull) << 32); 22 return ns; 23 } 24 25 int main() { 26 int T; 27 scanf("%d", &T); 28 for (int cas = 1; cas <= T; ++cas) { 29 int n; 30 scanf("%d", &n); 31 for (int i = 0; i < n; ++i) count[i].clear(); 32 std::vector<int> p(n); 33 uint64 candidate = (uint64(1) << n) - 1; 34 uint64 mask = candidate; 35 int cnt = 0; 36 for (int i = 0; i < n; ++i) { 37 scanf("%d", &p[i]); 38 --p[i]; 39 if (p[i] == -1) { 40 ++cnt; 41 } else { 42 candidate ^= uint64(1) << p[i]; 43 } 44 } 45 if (p[0] == -1) { 46 for (int i = 0; i < n; ++i) if (candidate >> i & 1) { 47 count[0].emplace_back(uint64(1) << i, uint64(1)); 48 } 49 } else { 50 count[0].emplace_back(uint64(1) << p[0], uint64(1)); 51 } 52 53 int64 ret = 1; 54 for (int i = 1; i <= cnt; ++i) { 55 ret = ret * i % mod; 56 } 57 58 for (int i = 1; i < n; ++i) { 59 if (p[i] == -1) { 60 for (auto &&e: count[i - 1]) { 61 auto s = e.first, ns = rev(s); 62 for (uint64 msk = candidate ^ (candidate & s); msk; ) { 63 int j = __builtin_ctzll(msk); 64 assert(~s >> j & 1); 65 uint64 z = (j <= 31) ? (ns >> (63 - 2 * j)) : (ns << (2 * j - 63)); 66 z &= mask; 67 if ((z | s) == s) { 68 count[i].emplace_back(s ^ (uint64(1) << j), e.second); 69 } 70 msk ^= uint64(1) << j; 71 } 72 } 73 } else { 74 for (auto &&e: count[i - 1]) { 75 auto s = e.first, ns = rev(s); 76 if (s >> p[i] & 1) continue; 77 ns = (p[i] <= 31) ? (ns >> (63 - 2 * p[i])) : (ns << (2 * p[i] - 63)); 78 ns &= mask; 79 if ((ns | s) == s) { 80 count[i].emplace_back(s | (uint64(1) << p[i]), e.second); 81 } 82 } 83 } 84 if (count[i].size()) { 85 std::sort(count[i].begin(), count[i].end()); 86 int m = 1; 87 for (size_t j = 1; j < count[i].size(); ++j) { 88 if (count[i][j].first != count[i][j - 1].first) count[i][m++] = count[i][j]; 89 else count[i][m - 1].second += count[i][j].second; 90 } 91 count[i].resize(m); 92 } 93 } 94 95 for (auto &&e: count[n - 1]) { 96 ret -= e.second; 97 ret = (ret % mod + mod) % mod; 98 } 99 printf("%lld\n", ret); 100 } 101 return 0; 102 }
