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@[TOC](AtCoder Beginner Contest 359)
这场我赛时打的非常不好,只做出了 2 2 2 题。
签到
// Problem: A - Count Takahashi // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_a // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; //# define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } signed main () { int n = rd (int); int ans = 0; for (int i = 1; i <= n; i ++ ) { string s; cin >> s; if (s == "Takahashi") ans ++ ; } printf ("%d\n", ans); return 0; }
签到
// Problem: B - Couples // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_b // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; //# define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") const int N = 105; template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } int n; vector <int> vec[N]; signed main () { n = rd (int); for (int i = 1; i <= 2 * n; i ++ ) { int x = rd (int); vec[x].push_back (i); } int ans = 0; for (int i = 1; i <= n; i ++ ) ans += (vec[i][1] - vec[i][0] == 2); printf ("%d\n", ans); return 0; }
首先,如果起点坐标或终点坐标在一个砖块的右侧时,把他变为在这个砖块的左侧不影响最终答案。
计算横坐标和纵坐标需要移动的格子数,分别记为
a
a
a,
b
b
b。
画图模拟可知:进行纵向运动时,可以免费向左或者向右移动一格。所以优先向上运动。
如果向上运动后,横坐标依旧没有达到目标值,那么就需要进行横向运动。可以发现,每花
1
1
1 块钱,可以横向移动
2
2
2 格,所以横向运动的花费为
max
(
0
,
a
−
b
)
2
\frac{\operatorname{max}(0,a-b)}{2}
2max(0,a−b)
// Problem: C - Tile Distance 2 // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_c // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; # define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } int sx, sy, ex, ey; signed main () { sx = rd (int), sy = rd (int), ex = rd (int), ey = rd (int); if ((sx + sy) % 2 == 1) sx -- ; if ((ex + ey) % 2 == 1) ex -- ; int a = abs (sx - ex), b = abs (sy - ey); printf ("%lld\n", b + max (0ll, a - b) / 2); return 0; }
把题目中的 A,B 转化为
0
0
0,
1
1
1。
d
p
i
,
s
dp_{i,s}
dpi,s 表示前
i
i
i 个字符中,最后
k
k
k 个字符为
s
s
s,保证没有长度为
k
k
k 的方案数
转移显然
// Problem: D - Avoid K Palindrome // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_d // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; //# define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") const int N = 1005, M = (1 << 10) + 5, mod = 998244353; template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } int n, k; string S; int dp[N][M]; bool checkpalin (int state) { for (int i = 0; i < k / 2; i ++ ) { if (((state >> i) ^ (state >> k - i - 1)) & 1) return 0; } return 1; } signed main () { cin >> n >> k >> S; dp[0][0] = 1; int ans = 0; for (int i = 1; i <= n; i ++ ) { for (int s = 0; s < (1 << k); s ++ ) { if (i >= k && checkpalin (s)) continue; if ((S[i - 1] == 'A' || S[i - 1] == '?') && s % 2 == 0) dp[i][s] = (dp[i][s] + (dp[i - 1][(s >> 1) + (1 << (k - 1))] + dp[i - 1][s >> 1])) % mod; if ((S[i - 1] == 'B' || S[i - 1] == '?') && s % 2 == 1) dp[i][s] = (dp[i][s] + (dp[i - 1][(s >> 1) + (1 << (k - 1))] + dp[i - 1][s >> 1])) % mod; if (i == n) ans = (ans + dp[i][s]) % mod; } } printf ("%d\n", ans); return 0; }
题目意思感觉有点抽象
对于每个挡板
i
i
i,找到在他前面第一个比他高的挡板
p
o
s
i
pos_i
posi(用单调栈),那么答案
a
n
s
i
ans_i
ansi 就可以从这个挡板继承过来。
a
n
s
i
=
a
n
s
p
o
s
i
+
(
i
−
p
o
s
i
)
×
a
i
ans_i=ans_{pos_i}+(i-pos_i)\times a_i
ansi=ansposi+(i−posi)×ai
// Problem: E - Water Tank // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_e // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; # define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") const int N = 200005; template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } int n; int a[N], pos[N]; int ans[N]; signed main () { n = rd (int); stack <pii> stk; for (int i = 1; i <= n; i ++ ) { a[i] = rd (int); while (!stk.empty () && stk.top ().fi < a[i]) stk.pop (); if (!stk.empty ()) pos[i] = stk.top().se; stk.push ({a[i], i}); } for (int i = 1; i <= n; i ++ ) { ans[i] = ans[pos[i]] + (i - pos[i]) * a[i]; printf ("%lld ", ans[i] + 1); } return 0; }
首先,因为这是一棵树,所以每个点的度数至少为
1
1
1
总度数为
2
×
n
−
2
2\times n - 2
2×n−2
我们可以进行贪心。在每个节点的度数都是
1
1
1 的基础上,考虑去动态安排度数,使得最终答案最小
对
i
i
i 号点考虑,如果度数从
d
i
d_i
di 变为
d
i
+
1
d_i+1
di+1:
原本贡献
d
i
2
×
a
i
d_i^2 \times a_i
di2×ai;
新的贡献:
(
d
i
+
1
)
2
×
a
i
=
(
d
i
2
+
2
×
d
i
+
1
)
×
a
i
(d_i+1)^2\times a_i=(d_i^2+2\times d_i+1)\times a_i
(di+1)2×ai=(di2+2×di+1)×ai
如果给
i
i
i 号点增加一个度数,造成的增量为
(
2
×
d
i
+
1
)
×
a
i
(2\times d_i+1)\times a_i
(2×di+1)×ai
每次选取最小的增量,加入答案。这一步可以使用 priority_queue
来实现
// Problem: F - Tree Degree Optimization // Contest: AtCoder - UNIQUE VISION Programming Contest 2024 Summer (AtCoder Beginner Contest 359) // URL: https://atcoder.jp/contests/abc359/tasks/abc359_f // Memory Limit: 1024 MB // Time Limit: 2000 ms // https://codeforces.com/problemset/customtest # include <bits/stdc++.h> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair <int, int> pii; # define int long long # define rd(t) read <t> () # define mem(a, b) memset (a, b, sizeof (a)) # define fi first # define se second # define lc u << 1 # define rc u << 1 | 1 # define debug printf ("debug\n") const int N = 200005; template <typename T> inline T read () { T s = 0; int w = 1; char c = getchar (); for (; !isdigit (c); c = getchar ()) { if (c == '-') w = -1; } for (; isdigit (c); c = getchar ()) s = (s << 1) + (s << 3) + c - '0'; return s * w; } int n; int a[N]; struct node { int x, y; bool operator < (const node &t) const { return (2 * x + 1) * y > (2 * t.x + 1) * t.y; } }; signed main () { n = rd (int); int ans = 0; for (int i = 1; i <= n; i ++ ) { a[i] = rd (int); ans += a[i]; } priority_queue <node> q; for (int i = 1; i <= n; i ++ ) q.push ({1, a[i]}); for (int i = 1; i < n - 1; i ++ ) { node u = q.top (); q.pop (); ans += (u.x * 2 + 1) * u.y; if (u.x < n - 1) q.push ({u.x + 1, u.y}); } printf ("%lld\n", ans); return 0; }
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