starmsg的专栏

class Solution {public: vector generateParenthesis(int n) { vector result; string path; dfs(n, 0, 0, path, result); return result; } void dfs(int n, int l,

注意细节。class Solution {public: vector spiralOrder(vector > &matrix) { vector result; int row = matrix.size(); if(row == 0) return result; int col = matrix

和Reverse Integer类似，按位处理，而不要转换成String。

DP+滚动数组。注意长度

题目描述：Given a string S and a string T, count the number of distinct subsequences ofT inS.A subsequence of a string is a new string which is formed from the original string by deleting some

DPclass Solution {public: bool wordBreak(string s, unordered_set &dict) { const int n = s.size(); if(n == 0) return true; vector f(n+1, false); f[0] = true;

A message containing letters from A-Z is being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message containing digits, determine the total nu

三种方法，第一种参考 http://blog.youkuaiyun.com/fightforyourdream/article/details/17711893Time O(n^3),

DP + 滚动数组，注意首行和首列特殊处理。

DP,  Time O(n^4), Space O(n^3)。

1. 2维 DP。class Solution {public: bool isInterleave(string s1, string s2, string s3) { const int n1 = s1.size(); const int n2 = s2.size(); const int n3 = s3.size();

DP.先利用DP计算每个substr是否

注意处理overflow和negative的问题。class Solution {public: int reverse(int x) { bool positive = (x>=0); x = abs(x); int result = 0; for(; x; x/=10)