代码随想录 Day3

​​​​​​209. 长度最小的子数组

int minSubArrayLen(int target, int* nums, int numsSize) { int left=0,sum=0,right=0,minlength=100001; for(right=0;right<numsSize;right++) { sum+=nums[right]; while (sum>=target) { minlength=fmin(minlength,right-left+1); sum=sum-nums[left]; left=left+1; } } return minlength==100001?0:minlength; }

笔记：

C语言取最小值用fmin()

子数组

滑动窗口

59. 螺旋矩阵 II

int** generateMatrix(int n, int* returnSize, int** returnColumnSizes) { int **matrix = (int**)malloc(n * sizeof(int*)); for(int i = 0; i < n; i++) matrix[i] = (int*)malloc(n * sizeof(int)); int top = 0, bottom = n - 1, left = 0, right = n - 1; int num = 1; while(num <= n * n) { // 上层：左→右 for(int i = left; i <= right; i++) matrix[top][i] = num++; top++; // 循环结束后更新 // 右层：上→下 for(int i = top; i <= bottom; i++) matrix[i][right] = num++; right--; // 下层：右→左 for(int i = right; i >= left; i--) matrix[bottom][i] = num++; bottom--; // 左层：下→上 for(int i = bottom; i >= top; i--) // 注意条件 >= matrix[i][left] = num++; left++; } *returnSize = n; *returnColumnSizes = (int*)malloc(n * sizeof(int)); for(int i = 0; i < n; i++) (*returnColumnSizes)[i] = n; return matrix; }

笔记：

重点是四个指针，以及他们更新的时机