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maxParaSubstring.java
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maxParaSubstring.java
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public class maxParaSubstring {
public static void main(String args[]) {
String str = "abcdzzcba";
System.out.println("longest para substring: " + para(str));
}
public static String para(String str) {
boolean dp[][] = new boolean[str.length()][str.length()];
int i, j;
int len;
int maxlen = 1;
int start = 0;
// for 1 char
for (i = 0; i < str.length(); i++)
dp[i][i] = true;
// for 2 adjacent chars
for (i = 0; i < str.length() - 1; i++) {
if (str.charAt(i) == str.charAt(i + 1)) {
dp[i][i + 1] = true;
maxlen = 2;
start = i;
}
}
// for different length
for (len = 3; len <= str.length(); len++) {
for (i = 0; i <= str.length() - len; i++) {
j = i + len - 1; // end char
dp[i][j] = dp[i + 1][j - 1] && str.charAt(i) == str.charAt(j);
if (dp[i][j] && len > maxlen) {
maxlen = len;
start = i;
}
}
}
return str.substring(start, start + maxlen);
}
}