# [leetcode] One Edit Distance

One Edit Distance

Given two strings S and T, determine if they are both one edit distance apart.

two pointers.

```class Solution {
public:
bool isOneEditDistance(string s, string t) {
int ls = s.size();
int lt = t.size();
if(abs(ls - lt) > 1) return false;
int i = 0, j = 0;
int dist = 0;
while(i < ls && j < lt){
if(s[i] != t[j]){
dist++;
if(dist > 1) break;
if(ls > lt){
j--; // do not move j
}
else if(ls < lt){
i--; // do not move i
}
}
i++;
j++;
}
// dist == 1 or only the last character is different.
return dist == 1 || (dist == 0 && ls != lt);
}
};```

```class Solution {
public:
bool isOneEditDistance(string s, string t) {
int distance = 0;
string tmp = s;
if(s.size() > t.size()){
s = t;
t = tmp;
}
if(t.size() - s.size() > 1) return false;
// replace
if(s.size() == t.size()){
for(int i = 0; i < s.size(); i++){
if(s[i] != t[i]){
distance++;
}
}
return distance == 1;
}

// s is shorter than t
if(s.size() == 0) return true;
for(int i = 0; i < s.size(); i++){
if(s[i] != t[i]){
t.erase(i, 1);
i--;
distance++;
}
if(distance > 1){
break;
}
}
return distance == 1 || distance == 0;
}
};```

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