传送门 一道神奇的DP………(鬼知道他为什么在tarjan里面) 一开始可能会考虑贪心或者什么其他神奇的算法,不过还是DP比较靠谱. 我们用f[i]表示摧毁所有i左侧的炸 药包最少需要的能量,用g[i]表示摧毁所有i右侧的炸 药包最少需要的能量. 那么我们只要找到满足j < i,a[i] - a[j] > f[j]+1的最后一个j炸 药包,就可以更新f[i]的值,f[i]  = min(f[i],a[i]-a[j],f[j]+1); 同样的g也是同理. 为什么这么找呢……因为首先我们发现如果a…

题目链接 Solution 应该可以用二分拿部分分,时间 \(O(n^2logn)\) . 然后可以考虑 \(n^2\) \(dp\) ,令 \(f_i\) 代表 \(i\) 点被激活,然后激活 \(i\) 之前所有点所需的半径. 那么很显然 \(f[i]=min(max(pos[i]-pos[j],f[j]))\) 其中 \(j<i\) . 再从后往前记录一个 \(g[i]\) , 那么答案就为 \(min(max(f[i],g[i]))\)以及还要考虑两点中间的,其中 \(1<=i<…

Angry Cows 题目描述:给出数轴上的\(n\)个整点\((a[i])\),现在要在数轴上选一个位置\(x\)(可以是实数),以及一个半径\(R\),在以\(x\)为中心,半径为\(R\)的范围内的点为被覆盖,然后被覆盖的点会以自己为中心,半径为\(R-1\)覆盖其它未被覆盖的点,以此类推,问覆盖所有点的最小\(R\) solution 这道题挺好的,可能我对于那些有单调性的题目不是很熟悉吧. 从小到大排序,首先算出以\(i\)为半径中心,覆盖前\(i\)个点的最小半径\(f[i]\),容…

P2868 [USACO07DEC]观光奶牛Sightseeing Cows [](https://www.cnblogs.com/images/cnblogs_com/Tony-Double-Sky/1270353/o_YH[_INPMKE_4RY]3DF(33@G.png) 错误日志: dfs 判负环没有把初值赋为 \(0\) 而是 \(INF\), 速度变慢 Solution 设现在走到了一个环, 环内有 \(n\) 个点, \(n\) 条边, 点权为 \(f_{i}\), 边权为 \(e…

P2868 [USACO07DEC]观光奶牛Sightseeing Cows 题目描述 Farmer John has decided to reward his cows for their hard work by taking them on a tour of the big city! The cows must decide how best to spend their free time. Fortunately, they have a detailed city map sh…

P3088 [USACO13NOV]挤奶牛Crowded Cows 题目描述 Farmer John's N cows (1 <= N <= 50,000) are grazing along a one-dimensional fence. Cow i is standing at location x(i) and has height h(i) (1 <= x(i),h(i) <= 1,000,000,000). A cow feels "crowded"…

NC24017 [USACO 2016 Jan S]Angry Cows 题目 题目描述 Bessie the cow has designed what she thinks will be the next big hit video game: "Angry Cows". The premise, which she believes is completely original, is that the player shoots cows with a slingshot i…

一图流 参考代码: #include<bits/stdc++.h> #define ll long long #define db double #define filein(a) freopen(#a".in","r",stdin) #define fileot(a) freopen(#a".out","w",stdout) #define sky fflush(stdout) #define gc getcha…

题目描述 Farmer John has decided to reward his cows for their hard work by taking them on a tour of the big city! The cows must decide how best to spend their free time. Fortunately, they have a detailed city map showing the L (2 ≤ L ≤ 1000) major landma…

题目描述 Farmer John has decided to reward his cows for their hard work by taking them on a tour of the big city! The cows must decide how best to spend their free time. Fortunately, they have a detailed city map showing the L (2 ≤ L ≤ 1000) major landma…