leetcode 字符串的排列

classSolution {
public:
boolcheckInclusion(strings1, strings2) {
intn=s1.length(), m=s2.length();
if (n>m) {
returnfalse;
        }
vector<int>cnt1(26), cnt2(26);
for (inti=0; i<n; ++i) {
++cnt1[s1[i] -'a'];
++cnt2[s2[i] -'a'];
        }
if (cnt1==cnt2) {
returntrue;
        }
for (inti=n; i<m; ++i) {
++cnt2[s2[i] -'a'];
--cnt2[s2[i-n] -'a'];
if (cnt1==cnt2) {
returntrue;
            }
        }
returnfalse;
    }
};