/**

public boolean isInterleave(String s1, String s2, String s3) {

// write your code here

int aLen = s1.length();

int bLen = s2.length();

int cLen = s3.length();

if (aLen == 0 || bLen == 0) {

return aLen == 0? s2.equals(s3) : s1.equals(s3);

}

if (cLen != (aLen + bLen)) {

return false;

}

boolean[][] dp = new boolean[aLen + 1][bLen + 1];

dp[0][0] = true;

// first row and col for empty string case.

for (int i = 1; i <= aLen; i++) {

char a = s1.charAt(i - 1);

char c = s3.charAt(i - 1);

if (a == c) {

dp[i][0] = dp[i - 1][0];

} else {

break;

}

}

for (int j = 1; j <= bLen; j++) {

char b = s2.charAt(j - 1);

char c = s3.charAt(j - 1);

if (b == c) {

dp[0][j] = dp[0][j - 1];

} else {

break;

}

}

for (int i = 1; i <= aLen; i++) {

for (int j = 1; j <= bLen; j++) {

char a = s1.charAt(i - 1);

char b = s2.charAt(j - 1);

char c = s3.charAt(i + j - 1);

if (a == c || b == c) {

dp[i][j] = (a == c && dp[i - 1][j]) || (b == c && dp[i][j - 1]);

} else {

dp[i][j] = false;

}

}

}

return dp[aLen][bLen];

}