Longest Word in Dictionary through Deleting

524. Longest Word in Dictionary through Deleting

Given a string and a string dictionary, find the longest string in the dictionary that can be formed by deleting some characters of the given string. If there are more than one possible results, return the longest word with the smallest lexicographical order.
If there is no possible result, return the empty string.

Example 1:

Input:
s = "abpcplea", d = ["ale","apple","monkey","plea"]

Output:
"apple"

Example 2:

Input:
s = "abpcplea", d = ["a","b","c"]

Output:
"a"

解析：关键分析string s能否通过删除一些字母得到string a,定义两个下标分别同时遍历两个字符串，对a中每个字符顺序遍历s找到相同的字符，当a遍历完成时，s如果没有遍历到结尾则可以通过删除得到a,否则不能

代码：

class Solution {
public:

string findLongestWord(string s, vector<string>& d) {
int strnum=d.size();
vector<string>ans;
string lastans="";
for (int i=0; i<strnum; i++)
{
string temp=d[i];
int ptemp=0;
int ps=0;
for (int j=0; j<temp.size(); j++)
{

while(ps<s.size()&&s[ps]!=temp[j])
{
ps++;
}

if (ps>=s.size())
{
ps++;
break;
}

else
{
ps++;
continue;
}
}

if (ps<=s.size())
{
if (temp.size()>=lastans.size())
{
if (temp.size()==lastans.size())
{
if (lastans>d[i]||lastans=="")
lastans=d[i];
}
else
{
lastans=d[i];
}

}

}
}

return lastans;

}
};