leetcode 第四天

2018年1月4日

15.（628）Maximum Product of Three Numbers

JAVA

class Solution {
    public int maximumProduct(int[] nums) {
        Arrays.sort(nums);
        return (nums[0]*nums[1]*nums[nums.length-1])>(nums[nums.length-1]*nums[nums.length-2]*nums[nums.length-3])?(nums[0]*nums[1]*nums[nums.length-1]):(nums[nums.length-1]*nums[nums.length-2]*nums[nums.length-3]);
    }
}

16.（628）==Maximum Product of Three Numbers==

JAVA

class Solution {
    public int thirdMax(int[] nums) {
        Integer first = null ,second = null,third = null;
        for(Integer n : nums){
            if(n.equals(first)||n.equals(second)||n.equals(third)) continue;
            if(first==null||n>first){
                third = second;
                second = first;
                first = n;
            }else if(second == null||n>second){
                third = second;
                second = n;
            }else if(third == null||n>third){
                third = n;
            }

        }

        return third == null?first:third;
    }

}

17.(643) Maximum Average Subarray I

JAVA

class Solution {
    public double findMaxAverage(int[] nums, int k) {
        double window = 0;
        double maxAvg = 0;
        for(int i =0;i<k;i++){
            window +=nums[i];
            maxAvg = window;
        }

        for(int i = k;i<nums.length;i++){
            window = window+nums[i]-nums[i-k];
            maxAvg = Math.max(maxAvg,window);

        }

        return maxAvg/k;
    }
}

18.(448) Find All Numbers Disappeared in an Array

JAVA

class Solution {
    public List<Integer> findDisappearedNumbers(int[] nums) {
        List<Integer> result = new ArrayList<Integer>();
        for(int i =0;i<nums.length;i++){

            nums[Math.abs(nums[i])-1] = -1 * Math.abs(nums[Math.abs(nums[i])-1]);
        }
        for(int i =0;i<nums.length;i++){
            if(nums[i]>0)
                result.add(i+1);
        }
        return result;
    }
}

19.(485) Max Consecutive Ones

JAVA

class Solution {
    public int findMaxConsecutiveOnes(int[] nums) {
        int max = 0;
        int times = 0;
        for(int i =0;i<nums.length;i++){
            if(nums[i]==1){
                times++;
                max = Math.max(max,times);
            }else{
                times = 0;
            }
        }
        return max;
    }
}

20.(88) Merge Sorted Array

JAVA

class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        while(n > 0){
            if(m>0)
                nums1[n+m-1] = nums1[m-1]>nums2[n-1]?nums1[--m]:nums2[--n];
            else
                nums1[n-1] = nums2[--n];
        }
    }
}

21.(605) Can Place Flowers

JAVA

class Solution {
    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        int count = 0;
        for(int i =0;i<flowerbed.length;i++){
            if(flowerbed[i]==0&&(i==0||flowerbed[i-1]==0)&&(i==flowerbed.length-1||flowerbed[i+1]==0)){
                count++;
                flowerbed[i]=1;
                if(count==n)
                    return true;
            }
        }
        return count >= n;
    }
}

原文地址：https://www.cnblogs.com/guoyaohua/p/8196716.html