代码随想录算法训练营第二天【数组part02】 | 977.有序数组的平方 、209.长度最小的子数组、59.螺旋矩阵II

977.有序数组的平方

题目链接：力扣（LeetCode）官网 - 全球极客挚爱的技术成长平台

求解思路：

代码：

class Solution {
public:
    vector sortedSquares(vector& nums) {
        int left = 0, right = nums.size()-1;
        vector result(nums.size());
        int index = nums.size()-1;
        while (left <= right){
            if (nums[left]*nums[left] > nums[right]*nums[right]){
                result[index] = (nums[left]*nums[left]);
                left++;
                index--;
            }
            else{
                result[index] = (nums[right]*nums[right]);
                right--;
                index--;
            }
        }
        return result;
    }
};

209.长度最小的子数组

题目链接：力扣（LeetCode）官网 - 全球极客挚爱的技术成长平台

求解思路：

代码：

class Solution {
public:
    int minSubArrayLen(int target, vector& nums) {
        int left = 0, right = 0;
        int result = INT_MAX;
        int sum = 0;
        //当右边界不会超出数组时，依次遍历元素并求和
        while (right < nums.size()){
            sum += nums[right];
            right++;
            //当和大于等于目标值
            //存储元素个数，从和中去掉第一个元素，left++
            while (sum >= target){
                result = min(result, right-left);
                sum -= nums[left];
                left++;
            }
        }
        return (result == INT_MAX) ? 0 : result;
    }
};

59.螺旋矩阵II

题目链接：

求解思路：

代码：

class Solution {
public:
    vector> generateMatrix(int n) {
        int left = 0, right = n-1, top = 0, bottom = n-1;
        vector> result(n,vector(n,0));
        int count = 1;
        while (count <= n*n){
            for (int i = left; i <= right; i++){
                result[top][i] = count;
                count++;
            }
            top++;
            for (int i = top; i <= bottom; i++){
                result[i][right] = count;
                count++;
            }
            right--;
            for (int i = right; i >= left; i--){
                result[bottom][i] = count;
                count++;
            }
            bottom--;
            for (int i = bottom; i >= top; i--){
                result[i][left] = count;
                count++;
            }
            left++;
        }
        return result;
    }
};