Day2|209.长度最小的子数组|59.螺旋矩阵II|区间和|开发商购买土地

209.长度最小的子数组

59.螺旋矩阵II

 209.长度最小的子数组

class Solution {
    public int minSubArrayLen(int target, int[] nums) {
            int fastIndex = 0;
            int slowIndex = 0;
            int sums = 0;
            int result = Integer.MAX_VALUE;
            for (fastIndex = 0; fastIndex < nums.length; fastIndex++) {
                sums += nums[fastIndex];
                while (sums >= target) { //直到小于或等于
                    if ((fastIndex - slowIndex + 1) <= result) {
                        result = (fastIndex - slowIndex + 1);
                    }
                    sums -= nums[slowIndex];
                    slowIndex ++;
                }
            }
            return result == Integer.MAX_VALUE ? 0 : result;
    }
}

59.螺旋矩阵II

class Solution {
    public int[][] generateMatrix(int n) {
        
        int x = 0; int y = 0;
        int[][] result = new int[n][n];
        int count = 1;
        for (int i = 0; i < n/2 + n % 2 ; i++ ) {
            //一轮一轮的填
            int sLength = n - 1 -2 * i;//填的长度
            for(int j = 0; j < sLength; j++) result[x][y++] = count++ ;
            for(int j = 0; j < sLength; j++) result[x++][y] = count++;
            for(int j = 0; j < sLength; j++) result[x][y--] = count++;
            for(int j = 0; j < sLength; j++) result[x--][y] = count++;
            x++;y++;
        }
        if (n % 2 ==1){
            result[n / 2][n / 2] = count;
        }
        return result;
    }
}