Prefix and leetcode2100. Suitable for bank robbery days

2100. Suitable for bank robbery

analysis

The prefix and

class Solution {
    
    public List<Integer> goodDaysToRobBank(int[] security, int time) {
    
int n = security.length;
        int[] dp1 = new int[n];
        int[] dp2 = new int[n];
        dp1[0] = 0;
        dp2[n-1] = 0;
        for (int i = 1; i < n; i++) {
    
            if (security[i] <= security[i-1]) {
    
                dp1[i] = dp1[i-1] + 1;
            }
        }
        for (int i = n -2; i >= 0; i--) {
    
            if (security[i] <= security[i+1]) {
    
                dp2[i] = dp2[i+1] + 1; 
            }
        }
        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
    
            if (dp1[i] >= time && dp2[i] >= time) {
    
                list.add(i);
            }
        }
        int[] ans = new int[list.size()];
        for (int i = 0; i < list.size(); i++) {
    
            ans[i] = list.get(i);
        }
        return list;
    }
}