/*
 * @lc app=leetcode id=567 lang=java
 *
 * [567] Permutation in String
 */

// @lc code=start
class Solution {
    public boolean checkInclusion(String s1, String s2) {
        if(s1.length() > s2.length()) {
            return false;
        }
        int[] c1 = strCompose(s1);
        int[] c2 = strCompose(s2.substring(0, s1.length()));
        boolean f = isComposeSame(c1, c2);
        int j = s1.length();
        while(!f && j < s2.length()) {
            c2[s2.charAt(j - s1.length())-'a']--;
            c2[s2.charAt(j)-'a']++;
            if(isComposeSame(c1, c2)) {
                f = true;
                break;
            }
            j++;
        }
        return f;
    }

    private int[] strCompose(String s) {
        int[] c = new int[26];
        for(int i = 0; i < s.length(); i++) {
            c[s.charAt(i)-'a']++;
        }
        return c;
    }

    private boolean isComposeSame(int[] a, int[] b) {
        if(a.length != b.length) {
            return false;
        }
        boolean matches = true;
        for(int i=0; i<a.length; i++) {
            if(a[i] != b[i]) {
                matches = false;
                break;
            }
        }
        return matches;
    }
}
// @lc code=end