leetcode 解题思路

Given an array of integerscostand an integertarget. Return themaximuminteger you can paintunder the following rules:The cost of painting adigit (i+1) is given bycost[i](0 indexed). The total cost used mustbe equal totarget. Integer does not ...

You haveddice, and each die hasffaces numbered1, 2, ..., f.Return the number of possible ways (out offdtotal ways)modulo10^9 + 7to roll the dice so the sum of the face up numbers equalsta...

Given a wooden stick of lengthnunits. The stick is labelled from0ton. For example, a stick of length6is labelled as follows:Given an integer arraycutswherecuts[i]denotes a position you should perform a cut at.You should perform the cuts in...

There are several stonesarranged in a row, and each stone has an associatedvalue which is an integer given in the arraystoneValue.In each round of the game, Alice divides the row intotwo non-empty rows(i.e. left row and right row), then Bob calculat...

There arenoranges in the kitchen and you decided to eat some of these oranges every day as follows:Eat one orange. If the number of remaining oranges (n) is divisible by 2 then you can eat n/2 oranges. If the number of remaining oranges (n) is divis...

DFS + Memo就是DP，注意cache存的物理意义，因为DFS是top down的，那么都是走到base case了，然后返回，那么存的结果就是从base case来的结果，那么就是存dp[0][0], dp[0][1] .. 一直到dp[n][target]. 最后返回的就是dp[n][ target]，还有个tricky的地方就是表示是否有值和是否访问过，解决方法就是存-1，代表没有访问...

Given a strings. In one step you can insert any character at any index of the string.Returnthe minimum number of stepsto makespalindrome.APalindrome Stringis one that reads the same backward as well as forward.Example 1:Input: s = "zzazz"O...

You have a keyboard layout as shown above in the XY plane, where each English uppercase letter is located at some coordinate, for example, the letterAis located at coordinate(0,0), the letterBis located at coordinate(0,1), the letterPis located a...

There are several cardsarranged in a row, and each card has an associated number of pointsThe points are given in the integer arraycardPoints.In one step, you can take one card from the beginning or from the end of the row. You have to take exactlyk...

We are playing the Guess Game. The game is as follows:I pick a number from1ton. You have to guess which number I picked.Every time you guess wrong, I'll tell you whether the number I picked is higher or lower.However, when you guess a particular n...

Given arows x colsmatrixgridrepresenting a field of cherries.Each cell ingridrepresents the number of cherries that you can collect.You have tworobots that can collect cherries for you, Robot #1 is located at the top-left corner (0,0) , and Robot...

You are given a tree withnnodes numbered from0ton-1in the form of a parent array whereparent[i]is the parent of nodei. The root of the tree is node0.Implement the functiongetKthAncestor(int node, int k)to return thek-th ancestor of the given...

You have a pointer at index0in an array of sizearrLen. At each step, you can move 1 position to the left, 1 position to the rightin the array or stay in the same place (The pointer should not be placed outside the array at any time).Given two intege...

You have agridof sizen x 3and you want to paint each cell of the grid with exactlyone of the three colours:Red,YelloworGreenwhile making sure that no two adjacent cells havethe same colour (i.e no two cells that share vertical or horizontal side...

Givennballoons, indexed from0ton-1. Each balloon is painted with a number on it represented by arraynums. You are asked to burst all the balloons. If the you burst ballooniyou will getnums[le...

Alexand Lee continue theirgames with piles of stones. There are a number ofpilesarranged in a row, and each pile has a positive integer number of stonespiles[i]. The objective of the game is to end with the moststones.Alex and Lee take turns, wi...

In a N x Ngridrepresenting a field of cherries, each cell is one of three possible integers.0 means the cell is empty, so you can pass through; 1 means the cell contains a cherry, that you can pi...

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.For example, given the following triangle[ [2], [3,4], [6,5...

Implement wildcard pattern matching with support for'?'and'*'.'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching should cover ...

Implement regular expression matching with support for'.'and'*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The matching should cover the entire input s...