leetcode：6109. Number of people who know the secret [definition of DP]

analysis

dp[i] It is defined as the first i Who just knows the secret
then dp[i] Is equal to dp[i - delay] To dp[i - forget] All and （ Specifically +1-1debug Besides, ）
And then at the end of the day forget Before dp Sum of

ac code

class Solution:
    def peopleAwareOfSecret(self, n: int, delay: int, forget: int) -> int:
        MOD = 10 ** 9 + 7
        ans = 0
        # dp[i]  Express   The first i How many people just know the secret 
        dp = [0] * (n + 1)
        #print(dp)
        dp[1] = 1
        
        for i in range(2, n + 1):
            for j in range(i - forget + 1, i - delay + 1):
                if j >= 1:
                    dp[i] += dp[j]
                    
        
        for i in range(forget):
            ans += dp[n - i]
            ans %= MOD
        return ans
                    
        

summary

dp[i] What does it mean
How to state transition