438. Find All Anagrams in a String

class Solution {
    public List<Integer> findAnagrams(String s, String p) {
        
        List<Integer> res = new ArrayList<>();
        int[] map = new int[256];
        
        if (s.length() == 0 || s == null || p.length()==0 || p == null){
            return res;
        }
        
        //记录一下p中char的个数
        for (char cur : p.toCharArray()){
            map[cur]++;
        }
        
        int left = 0;
        int right = 0;
        int count = p.length();
        
        while(right < s.length()){
            //判断当前right位置的char是否大于0
            if (map[s.charAt(right)] > 0){
                count--;
            }
            map[s.charAt(right)]--;
            right++;
            
            if(count == 0){
                res.add(left);
            }
            if(right - left == p.length()){
                if (map[s.charAt(left)] >= 0){
                    count++;
                }
                map[s.charAt(left)]++;
                left++;
            }
        }
        return res;
    }
}

 

转载于:https://my.oschina.net/u/3457852/blog/1538535