/**

public int countSubstrings(String s) {

if (s == null || s.length() < 1) return 0;

char[] chars = s.toCharArray();

int ans = 0;

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

StringBuilder sb = new StringBuilder();

for (int j = i; j < chars.length; j++) {

if (isRecStr(sb.append(String.valueOf(chars[j])).toString())) ans++;

}

}

return ans;

}

private boolean isRecStr(String str) {

int end = str.length() - 1;

int start = 0;

while (start <= end) {

if (str.charAt(start++) != str.charAt(end--)) return false;

}

return true;

}

/**

public int countSubstrings_dp(String s) {

boolean[][] dp = new boolean[s.length()][s.length()];

int ans = 0;

for (int j = 0; j < s.length(); j++) {

for (int i = 0; i <= j; i++) {

if (s.charAt(i) == s.charAt(j) && (j - i < 2 || dp[i + 1][j - 1])) {

dp[i][j] = true;

ans++;

}

}

}

return ans;

}

@Test

public void test() {

System.out.println(countSubstrings("aba"));

}