剑指offer专项突击版 --- 第 3 天

class Solution {
    
    public List<List<Integer>> threeSum(int[] nums) {
    
        List<List<Integer>> ans = new ArrayList<>();
        Arrays.sort(nums);
        for(int i = 0; i < nums.length - 2; i++){
    
            if(nums[i] > 0){
    
                break;
            }
            if (i > 0 && nums[i] == nums[i - 1]) continue;
            int left = i + 1;
            int right = nums.length - 1;
            while(left < right){
    
                if(nums[i] + nums[left] + nums[right] == 0){
    
                    List<Integer> list = new ArrayList<>();
                    list.add(nums[i]);
                    list.add(nums[left]);
                    list.add(nums[right]);
                    ans.add(list);
                    while (left < right && nums[left] == nums[left +1]){
    
                        left++;
                    }
                    left++;
                    while (left < right && nums[right] == nums[right -1]){
    
                        right--;
                    }
                    right--;
                }else if(nums[i] + nums[left] + nums[right] > 0){
    
                    right--;
                }else{
    
                    left++;
                }
            }
        }
        return ans;
    }
}

class Solution {
    
    public int minSubArrayLen(int target, int[] nums) {
    
        int n = nums.length;
        if(n <= 0){
    
            return 0;
        }
        int ans = Integer.MAX_VALUE;
        int end = 0;
        int start = 0;
        int sum = 0;
        while(end < n){
    
            sum += nums[end];
            while(sum >= target){
    
                ans = Math.min(ans, end - start + 1);
                sum -= nums[start];
                start++;
            }
            end++;
        }
        return ans == Integer.MAX_VALUE ? 0 : ans;

    }
}

class Solution {
    
    public int numSubarrayProductLessThanK(int[] nums, int k) {
    
        int left = 0;
        int ret = 0;
        int total = 1;
        for (int right = 0; right < nums.length; right++) {
    
            total *= nums[right];
            while (left <= right && total >= k) {
    
                total /= nums[left];
                left++;
            }
            if (left <= right) {
    
                ret += right - left + 1;
            }
        }
        return ret;
    }
}