_132_PalindromePartitioningII.java

package leetcode_1To300;

/**
 * 本代码来自 Cspiration，由 @Cspiration 提供
 * 题目来源：http://leetcode.com
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 */
public class _132_PalindromePartitioningII {
    /**
     * 132. Palindrome Partitioning II
     * Given a string s, partition s such that every substring of the partition is a palindrome.

     Return the minimum cuts needed for a palindrome partitioning of s.

     For example, given s = "aab",
     Return 1 since the palindrome partitioning ["aa","b"] could be produced using 1 cut.

     [][] isPalindrome
     [] cuts
     i   j
     abcba s.charAt(i) = s.charAt(j) && isPalindrome[i+1][j-1]


     time : O(n^2)
     space : O(n^2)

     * @param s
     * @return
     */

    public int minCut(String s) {
        if (s == null || s.length() == 0) return 0;
        int len = s.length();
        int[] cuts = new int[len];
        boolean[][] isPalindrome = new boolean[len][len];

        for (int i = 0; i < len; i++) {
            int min = i;
            for (int j = 0; j <= i; j++) {
                if (s.charAt(i) == s.charAt(j) && (i - j < 2 || isPalindrome[j + 1][i - 1])) {
                    isPalindrome[j][i] = true;
                    min = j == 0 ? 0 : Math.min(min, cuts[j - 1] + 1);
                }
            }
            cuts[i] = min;
        }
        return cuts[len - 1];
    }
}