C++: Local map variable doesn't work but global one works
$begingroup$
#include <unordered_map>
class Solution {
public:
// std::unordered_map<int, int> m; <<---- this one works
int size;
/**
* @param s: a string, encoded message
* @return: an integer, the number of ways decoding
*/
int numDecodings(string &s) {
// write your code here
size = s.length();
if(!size) return 0;
std::unordered_map<int, int> m; <<---- this doesn't work
decode(s, 0, m);
}
/**
* Time : O(n), Space: O(1)
*/
int decode(string &s, int i, std::unordered_map<int, int>& m) {
if (m.count(i)) { return m[i]; }
if (s[i] == '0') return 0;
if (size == 1) return 1;
if (i >= size - 1) return 1;
int ways = decode(s, i + 1, m);
int prefix = (s[i] - '0') * 10 + (s[i + 1] - '0');
if (prefix <= 26) {
ways += decode(s, i + 2, m);
}
m[i] = ways;
return ways;
}
};
I am trying to do an exercise in LintCode but my code doesn't work if I use a local map variable but works fine by a global map.
Can anyone help to see what is going wrong here? thanks !
c++
$endgroup$
add a comment |
$begingroup$
#include <unordered_map>
class Solution {
public:
// std::unordered_map<int, int> m; <<---- this one works
int size;
/**
* @param s: a string, encoded message
* @return: an integer, the number of ways decoding
*/
int numDecodings(string &s) {
// write your code here
size = s.length();
if(!size) return 0;
std::unordered_map<int, int> m; <<---- this doesn't work
decode(s, 0, m);
}
/**
* Time : O(n), Space: O(1)
*/
int decode(string &s, int i, std::unordered_map<int, int>& m) {
if (m.count(i)) { return m[i]; }
if (s[i] == '0') return 0;
if (size == 1) return 1;
if (i >= size - 1) return 1;
int ways = decode(s, i + 1, m);
int prefix = (s[i] - '0') * 10 + (s[i + 1] - '0');
if (prefix <= 26) {
ways += decode(s, i + 2, m);
}
m[i] = ways;
return ways;
}
};
I am trying to do an exercise in LintCode but my code doesn't work if I use a local map variable but works fine by a global map.
Can anyone help to see what is going wrong here? thanks !
c++
$endgroup$
add a comment |
$begingroup$
#include <unordered_map>
class Solution {
public:
// std::unordered_map<int, int> m; <<---- this one works
int size;
/**
* @param s: a string, encoded message
* @return: an integer, the number of ways decoding
*/
int numDecodings(string &s) {
// write your code here
size = s.length();
if(!size) return 0;
std::unordered_map<int, int> m; <<---- this doesn't work
decode(s, 0, m);
}
/**
* Time : O(n), Space: O(1)
*/
int decode(string &s, int i, std::unordered_map<int, int>& m) {
if (m.count(i)) { return m[i]; }
if (s[i] == '0') return 0;
if (size == 1) return 1;
if (i >= size - 1) return 1;
int ways = decode(s, i + 1, m);
int prefix = (s[i] - '0') * 10 + (s[i + 1] - '0');
if (prefix <= 26) {
ways += decode(s, i + 2, m);
}
m[i] = ways;
return ways;
}
};
I am trying to do an exercise in LintCode but my code doesn't work if I use a local map variable but works fine by a global map.
Can anyone help to see what is going wrong here? thanks !
c++
$endgroup$
#include <unordered_map>
class Solution {
public:
// std::unordered_map<int, int> m; <<---- this one works
int size;
/**
* @param s: a string, encoded message
* @return: an integer, the number of ways decoding
*/
int numDecodings(string &s) {
// write your code here
size = s.length();
if(!size) return 0;
std::unordered_map<int, int> m; <<---- this doesn't work
decode(s, 0, m);
}
/**
* Time : O(n), Space: O(1)
*/
int decode(string &s, int i, std::unordered_map<int, int>& m) {
if (m.count(i)) { return m[i]; }
if (s[i] == '0') return 0;
if (size == 1) return 1;
if (i >= size - 1) return 1;
int ways = decode(s, i + 1, m);
int prefix = (s[i] - '0') * 10 + (s[i + 1] - '0');
if (prefix <= 26) {
ways += decode(s, i + 2, m);
}
m[i] = ways;
return ways;
}
};
I am trying to do an exercise in LintCode but my code doesn't work if I use a local map variable but works fine by a global map.
Can anyone help to see what is going wrong here? thanks !
c++
c++
asked 14 mins ago
MrROYMrROY
136114
136114
add a comment |
add a comment |
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