代码随想录算法训练营天 第九章 五十五天| 392.判断子序列 115.不同的子序列

代码随想录算法训练营天 第九章 五十五天| 392.判断子序列 115.不同的子序列

392.判断子序列

class Solution {
    public boolean isSubsequence(String s, String t) {
        int[][] dp = new int[s.length()+1][t.length()+1];

        for (int i = 1; i <= s.length(); i++) {
            char char1 = s.charAt(i-1);
            for (int j = 1; j <= t.length(); j++) {
                char char2 = t.charAt(j-1);
                if (char1 == char2) {
                    dp[i][j] = dp[i-1][j-1] + 1;
                } else {
                    dp[i][j] = dp[i][j-1];
                }
            }
        }
        return dp[s.length()][t.length()] == s.length();
    }
}

115.不同的子序列

class Solution {
    public int numDistinct(String s, String t) {
        int[][] dp = new int[s.length()+1][t.length()+1];
        for (int i = 0; i <= s.length(); i++) {
            dp[i][0] = 1;
        }
        for (int j = 1; j <= t.length(); j++) {
            dp[0][j] = 0;
        }
        for (int i = 1; i <= s.length(); i++) {
            char char1 = s.charAt(i-1);
            for (int j = 1; j <= t.length(); j++) {
                char char2 = t.charAt(j-1);
                if (char1 == char2) {
                    dp[i][j] = dp[i-1][j-1] + dp[i-1][j];
                } else {
                    dp[i][j] = dp[i-1][j];
                }
            }
        }
        return dp[s.length()][t.length()];
    }
}