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Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.DFS，我们只要叶子节点，和之前的Maximum Depth有点不一样 1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 ... 阅读全文
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Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array[−2,1,−3,4,−1,2,1,−5,4],the contiguous subarray[4,−1,2,1]has the largest sum =6.More practice:If you have figured out the O(n) solution, try coding another solution usi 阅读全文
摘要：
Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.用DFS搞定 1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * ... 阅读全文
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Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.DP。用f[i][j]来记录i行以j列为结尾，往前连续的1的个数。然后再一个O(n^3)的循环来找以(i, j)为右下角的矩形最大的1的面积。 1 class Solution { 2 private: 3 int f[1000][1000]; 4 public: 5 int maximalRectangle(vector<vector< 阅读全文
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Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.用 阅读全文
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Given a stringS, find the longest palindromic substring inS. You may assume that the maximum length ofSis 1000, and there exists one unique longest palindromic substring.用一个指针从0遍历到s.size()-1，从里向外来检测子串是否是回文，分两种情况：1）bab, 2)bb。也就是当前指针可能指向的是奇数回文，也可能是偶数回文。做两次检测。 1 class Solution { 2 public: 3 string ... 阅读全文
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Write a function to find the longest common prefix string amongst an array of strings.模拟法，先选取第一个字符串，之后依次和后面的字符串得出LCP 1 class Solution { 2 public: 3 string longestCommonPrefix(vector<string> &strs) { 4 // Start typing your C/C++ solution below 5 // DO NOT write int main() function... 阅读全文
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Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Input:Digit string "23"Output: ["ad", "ae", "af", "bd", "be", &q 阅读全文
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Given a stringsconsists of upper/lower-case alphabets and empty space characters' ', return the length of last word in the string.If the last word does not exist, return 0.Note:A word is defined as a character sequence consists of non-space characters only.For example,Givens="Hello Worl 阅读全文
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Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Determine if you are able to reach the last index.For example:A =[2,3,1,1,4], returntrue.A =[3,2,1,0,4], returnfalse.用贪 阅读全文