剑指offer基础版 ---- 第29天

class Solution {
    
    public boolean isMatch(String s, String p) {
    
        int m = s.length();
        int n = p.length();

        boolean[][] f = new boolean[m + 1][n + 1];
        f[0][0] = true;
        for (int i = 0; i <= m; ++i) {
    
            for (int j = 1; j <= n; ++j) {
    
                if (p.charAt(j - 1) == '*') {
    
                    f[i][j] = f[i][j - 2];
                    if (matches(s, p, i, j - 1)) {
    
                        f[i][j] = f[i][j] || f[i - 1][j];
                    }
                } else {
    
                    if (matches(s, p, i, j)) {
    
                        f[i][j] = f[i - 1][j - 1];
                    }
                }
            }
        }
        return f[m][n];
    }

    public boolean matches(String s, String p, int i, int j) {
    
        if (i == 0) {
    
            return false;
        }
        if (p.charAt(j - 1) == '.') {
    
            return true;
        }
        return s.charAt(i - 1) == p.charAt(j - 1);
    }
}

class Solution {
    
    public int nthUglyNumber(int n) {
    
        int[] factors = {
    2, 3, 5};
        Set<Long> seen = new HashSet<Long>();
        PriorityQueue<Long> heap = new PriorityQueue<Long>();
        seen.add(1L);
        heap.offer(1L);
        int ugly = 0;
        for (int i = 0; i < n; i++) {
    
            long curr = heap.poll();
            ugly = (int) curr;
            for (int factor : factors) {
    
                long next = curr * factor;
                if (seen.add(next)) {
    
                    heap.offer(next);
                }
            }
        }
        return ugly;
    }
}

class Solution {
    
    public double[] dicesProbability(int n) {
    
        double[] dp = new double[6];
        Arrays.fill(dp, 1.0 / 6.0);
        for (int i = 2; i <= n; i++) {
    
            double[] tmp = new double[5 * i + 1];
            for (int j = 0; j < dp.length; j++) {
    
                for (int k = 0; k < 6; k++) {
    
                    tmp[j + k] += dp[j] / 6.0;
                }
            }
            dp = tmp;
        }
        return dp;
    }
}