Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn’t one, return 0 instead.
For example, given the array [2,3,1,2,4,3] and s = 7, the subarray [4,3] has the minimal length under the problem constraint
思路：尺取即可。。好久没写，竟然调了半天。。。
代码实现 1/* *********************************************** 2Author :111qqz 3Created Time :2017年04月13日 星期四 20时48分00秒 4File Name :209.cpp 5************************************************ */ 6class Solution { 7 8public: 9 10 int ruler(vector<int>nums,int tar,int n) 11 { 12 int head = 0; 13 int tail = 0; 14 int sum = 0 ; 15 int res = 0x3f3f3f3f; 16 while (tail<n&&head<=tail) 17 { 18 sum = sum + nums[tail]; 19 if (sum>=tar) 20 { 21 res = min(res,tail-head+1); 22 while (sum>=tar&&head<tail) 23 { 24 sum-=nums[head]; 25 head++; 26 } 27 if (sum>=tar) 28 { 29 res = min(res,tail-head+1); 30 } 31 else 32 { 33 head--; 34 sum+=nums[head]; 35 res = min(res,tail-head+1); 36 } 37 } 38 39 40 41 tail++; 42 } 43 return res==0x3f3f3f3f?0:res; 44 } 45 46 47 int minSubArrayLen(int s, vector<int>& nums) { 48 int n = nums.size(); 49 int res = ruler(nums,s,n); 50 return res; 51 52 53 } 54 55};
Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.
Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.
题意：一个数组，由0,1,2组成，现在要求升序排列
思路：无脑做法就是计数排序，扫两遍，时间复杂度O(n)，空间复杂度O(1)
Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.
Note: You may not slant the container and n is at least 2.
题意：n条竖直的线段 (i,0)->(i,a[i])，从中选2条，和x轴共同组成一个开口的容器，问容器的最大面积。
Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.
思路： 排序，然后two pointer，复杂度 O(n^2)
1/* *********************************************** 2Author :111qqz 3Created Time :2017年04月13日 星期四 16时24分28秒 4File Name :16.cpp 5************************************************ */ 6class Solution { 7 8public: 9 10 int n; 11 int threeSumClosest(vector<int>& nums, int target) { 12 n = nums.size(); 13 sort(nums.begin(),nums.end()); 14 int mn = 0x3f3f3f3f; 15 int x,y,z; 16 for ( int i = 0 ; i <=n-3 ; i++) 17 { 18 int head = i+1; 19 int tail = n-1; 20 int tar = target - nums[i]; 21 while (head<tail) 22 { 23 int cur = target-nums[i]-nums[head]-nums[tail]; 24 if (abs(cur)<mn) 25 { 26 mn = abs(cur); 27 x = nums[i]; 28 y = nums[head]; 29 z = nums[tail]; 30 } 31 if (nums[head]+nums[tail]==tar) return target; 32 if (nums[head]+nums[tail]<tar) head++; 33 else tail--; 34 } 35 } 36 return x + y + z; 37 38 39 40 41 } 42 43};
Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.
Note: The solution set must not contain duplicate quadruplets.
思路： O(n^2)枚举两个元素，变成2-sum问题，总体复杂度O(n^3)
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Note: The solution set must not contain duplicate triplets.
思路：排序O(nlgn)，然后枚举一个元素O(n)，对于每个元素，在剩下的区间中 two pointer O(n)
题目链接
题意：
how many pairs of integers l and r are there, such that 1 ≤ l < r ≤ n and sequence b = _a_1_a_2… a__l__a__r__a__r + 1… a__n has no more than k inversions.
我花了两个小时才看懂题。。。。一直没懂b数列中a[l]和a[r]怎么就挨着了。。。
其实意思是。。。只保留a数列中1..l和r..n的。。。构成b数列。。。然后b数列的逆序对数小于等于k.问这样的l,r的对数。
B. Kefa and Company
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Kefa wants to celebrate his first big salary by going to restaurant. However, he needs company.
Kefa has n friends, each friend will agree to go to the restaurant if Kefa asks. Each friend is characterized by the amount of money he has and the friendship factor in respect to Kefa. The parrot doesn’t want any friend to feel poor compared to somebody else in the company (Kefa doesn’t count). A friend feels poor if in the company there is someone who has at least d units of money more than he does. Also, Kefa wants the total friendship factor of the members of the company to be maximum. Help him invite an optimal company!
Jessica’s Reading Problem
Time Limit Memory Limit Total Submissions Accepted 1000MS 65536K 8787 2824 Description
Jessica’s a very lovely girl wooed by lots of boys. Recently she has a problem. The final exam is coming, yet she has spent little time on it. If she wants to pass it, she has to master all ideas included in a very thick text book. The author of that text book, like other authors, is extremely fussy about the ideas, thus some ideas are covered more than once. Jessica think if she managed to read each idea at least once, she can pass the exam. She decides to read only one contiguous part of the book which contains all ideas covered by the entire book. And of course, the sub-book should be as thin as possible.