ACM--单调栈--Bad Hair Day--POJ--3250--水
2016-04-16 15:49
459 查看
POJ地址:http://poj.org/problem?id=3250
Bad Hair Day
Description
Some of Farmer John's N cows (1 ≤ N ≤ 80,000) are having a bad hair day! Since each cow is self-conscious about her messy hairstyle, FJ wants to count the number of other cows that can see the top of other cows' heads.
Each cow i has a specified height hi (1 ≤ hi ≤ 1,000,000,000) and is standing in a line of cows all facing east (to the right in our diagrams). Therefore, cow i can see the tops of the heads of cows
in front of her (namely cowsi+1, i+2, and so on), for as long as these cows are strictly shorter than cow i.
Consider this example:
Cow#1 can see the hairstyle of cows #2, 3, 4
Cow#2 can see no cow's hairstyle
Cow#3 can see the hairstyle of cow #4
Cow#4 can see no cow's hairstyle
Cow#5 can see the hairstyle of cow 6
Cow#6 can see no cows at all!
Let ci denote the number of cows whose hairstyle is visible from cow i; please compute the sum of c1 through cN.For this example, the desired is answer 3 + 0 + 1 + 0 + 1 + 0 = 5.
Input
Line 1: The number of cows, N.
Lines 2..N+1: Line i+1 contains a single integer that is the height of cow i.
Output
Line 1: A single integer that is the sum of c1 through cN.
Sample Input
Sample Output
================================华丽的分割线=============================
单调栈的入门题:单调栈就是维护一个栈,栈中的元素都保持着单调递增或递减的顺序。
题目意思:有n只牛站在一排,给出队伍中每只牛的高度,每只牛只能看到它右边比它矮的牛,求所有的牛能看到的牛数之和。
当我们新加入一个高度值时,如果栈中存在元素小于新加入的高度值,那这个牛肯定看不见这个高度的牛,就把这个元素弹栈。
每次加入新元素,并执行完弹出操作后,栈中元素个数便是可以看见这个牛的“牛数”。
Bad Hair Day
Description
Some of Farmer John's N cows (1 ≤ N ≤ 80,000) are having a bad hair day! Since each cow is self-conscious about her messy hairstyle, FJ wants to count the number of other cows that can see the top of other cows' heads.
Each cow i has a specified height hi (1 ≤ hi ≤ 1,000,000,000) and is standing in a line of cows all facing east (to the right in our diagrams). Therefore, cow i can see the tops of the heads of cows
in front of her (namely cowsi+1, i+2, and so on), for as long as these cows are strictly shorter than cow i.
Consider this example:
= = = = - = Cows facing right --> = = = = - = = = = = = = = = 1 2 3 4 5 6
Cow#1 can see the hairstyle of cows #2, 3, 4
Cow#2 can see no cow's hairstyle
Cow#3 can see the hairstyle of cow #4
Cow#4 can see no cow's hairstyle
Cow#5 can see the hairstyle of cow 6
Cow#6 can see no cows at all!
Let ci denote the number of cows whose hairstyle is visible from cow i; please compute the sum of c1 through cN.For this example, the desired is answer 3 + 0 + 1 + 0 + 1 + 0 = 5.
Input
Line 1: The number of cows, N.
Lines 2..N+1: Line i+1 contains a single integer that is the height of cow i.
Output
Line 1: A single integer that is the sum of c1 through cN.
Sample Input
6 10 3 7 4 12 2
Sample Output
5
================================华丽的分割线=============================
单调栈的入门题:单调栈就是维护一个栈,栈中的元素都保持着单调递增或递减的顺序。
题目意思:有n只牛站在一排,给出队伍中每只牛的高度,每只牛只能看到它右边比它矮的牛,求所有的牛能看到的牛数之和。
当我们新加入一个高度值时,如果栈中存在元素小于新加入的高度值,那这个牛肯定看不见这个高度的牛,就把这个元素弹栈。
每次加入新元素,并执行完弹出操作后,栈中元素个数便是可以看见这个牛的“牛数”。
#include<iostream> #include<cstdio> #include<stack> using namespace std; int main(void){ int n; stack <long long>sta; if(scanf("%d",&n)!=EOF){ long long result=0; long long x; cin>>x; //将第一个元素入栈 sta.push(x); for(int i=1;i<n;i++){ cin>>x; while(!sta.empty()&&sta.top()<=x){ sta.pop(); } result+=sta.size(); sta.push(x); } cout<<result<<endl; //清空栈 while(!sta.empty()){ sta.pop(); } } return 0; }
相关文章推荐
- Again Stone Game (通过SG函数找规律)
- 《LeetBook》leetcode题解(11):Container With Most Water[M] ——用两个指针在数组内移动
- 食物链(带权并查集)(OpenJ_Bailian 1182)
- 11. Container With Most Water
- vim 插件之vim-trailing-whitespace
- 人工智能\机器学习\统计学\数据挖掘之间有什么区别?
- 信息: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logge
- HDU 1021 Fibonacci Again(斐波那契数列+mod规律)
- tools:context=".MainActivity"
- Code Forces 22B Bargaining Table
- Code Forces 22B Bargaining Table
- USACO Training Section 3.2 & 洛谷P2730
- Educational Codeforces Round 8 F. Bear and Fair Set【最大流】
- [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:31:compile (default-co
- 1014. Waiting in Line
- leetcode 70. Climbing Stairs
- 对话人工智能专家-吴恩达等人 重要总结
- NDCG Normalized discounted cumulative gain 理解分析
- 人工智能60年:介绍深度学习的一本好书
- 无线破解攻击工具Aircrack-ng使用详解