public boolean isOneEditDistance(String s, String t) {

int lens = s.length();

int lent = t.length();

if (Math.abs(lens - lent) > 1) return false;

if (lens > lent) {

return isOneDelete(s, t);

} else if (lent > lens) {

return isOneDelete(t, s);

} else {

return isOneReplace(s, t);

}

}

private boolean isOneReplace(String s, String t) {

int diff = 0;

char[] charss = s.toCharArray();

char[] charst = t.toCharArray();

for (int i=0; i<charss.length; i++) {

if (charss[i] != charst[i]) {

diff++;

if (diff > 1) return false;

}

}

return diff == 1;

}

private boolean isOneDelete(String longStr, String shortStr) {

char[] charsl = longStr.toCharArray();

char[] charss = shortStr.toCharArray();

int l = 0;

int s = 0;

int diff = 0;

while (s < charss.length && l < charsl.length) {

if (charss[s] != charsl[l]) {

diff++;

if (diff > 1) return false;

l++;

} else {

s++;

l++;

}

}

return ((l - s) == 1 && diff == 1) || (s == l && diff == 0);

}

public boolean isOneEditDistance2(String s, String t) {

if (s == null || t == null || Math.abs(s.length() - t.length()) >= 2) return false;

char[] cs = s.toCharArray();

int lenS = s.length();

char[] ct = t.toCharArray();

int lenT = t.length();

int i = 0;

int j = 0;

while (i < lenS && j < lenT) {

if (cs[i] == ct[j]) {

i++;

j++;

continue;

}

return isSame(cs, i+1, lenS, ct, j+1, lenT) || isSame(cs, i+1, lenS, ct, j, lenT) || isSame(cs, i, lenS, ct, j+1, lenT);

}

return Math.abs(lenS - lenT) == 1;

}

private boolean isSame(char[] cs, int i, int lenS, char[] ct, int j, int lenT) {

if (i == lenS && j == lenT) return true;

if (i == lenS || j == lenT) return false;

while (i < lenS && j < lenT) {

if (cs[i++] != ct[j++]) return false;

}

return i == lenS && j == lenT;

}