【LeetCode】1248.统计[优美子数组]

/*
	使用数组odd存储奇数下标
*/
class Solution {
public:
    int numberOfSubarrays(vector<int>& nums, int k) {
        int odd_s = 0, ans = 0;
        int n = nums.size();
        vector<int> odd(n+2);
        for(int i=0; i<n; i++) {
            if(nums[i]%2) odd[++odd_s] = i;
        }
        odd[0] = -1;
        odd[++odd_s] = n;
        for(int i=1; i+k<=odd_s; i++) {
            ans += (odd[i]-odd[i-1])*(odd[i+k]-odd[i+k-1]);
        }
        return ans;
    }
};