【题目】给定一个字符串str，返回把str全部切成回文子串的最小分割数。

public class MinCut {
	public static int minCut(String str) {
		if (str == null || str.equals("")) {
			return 0;
		}
		char[] chas = str.toCharArray();
		int len = chas.length;
		int[] dp = new int[len + 1];// dp数组
		boolean[][] b = new boolean[len][len];
		dp[len - 1] = -1;
		for (int i = len - 1; i > -1; i--) {
			dp[i] = Integer.MAX_VALUE;
			for (int j = i; j < len; j++) {
				if (chas[i] == chas[j] && (j - i < 2 || b[i + 1][j - 1])) {
					b[i][j] = true;
					dp[i] = Math.min(dp[i], dp[j + 1] + 1);
				}
			}
		}
		return dp[0];
	}
}