73. 矩阵置零
class Solution {
public:void setZeroes(vector<vector<int>>& a) {int n = a.size(), m = a[0].size();vector<int> r(n + 10, 0);vector<int> c(m + 10, 0);for (int i = 0; i < n; i++) {for (int j = 0; j < m; j++) {if (!a[i][j]) {r[i] = 1;c[j] = 1;}}}for (int i = 0; i < n; i++) {for (int j = 0; j < m; j++) {if (r[i] || c[j]) a[i][j] = 0;}}}
};模拟
54. 螺旋矩阵
class Solution {
public:vector<int> spiralOrder(vector<vector<int>>& a) {int n = a.size(), m = a[0].size();int x = 0, y = 0;int sum = m * n;int sx = n - 1, sy = m;int dx = 1, dy = 1;vector<int> ans;while (sum) {for (int i = 1; i <= sy; i++) {ans.push_back(a[x][y]);y += dy;sum--;}dy *= -1;sy--;x += dx;y += dy;for (int i = 1; i <= sx; i++) {ans.push_back(a[x][y]);x += dx;sum--;}dx *= -1;sx--;y += dy;x += dx;}return ans;}
};套路题，模拟
48. 旋转图像
class Solution {
public:void rotate(vector<vector<int>>& a) {int n = a.size(), m = a[0].size();vector<vector<int>> ans(n, vector<int>(m, 0));for (int i = 0; i < n; i++) {for (int j = 0; j < m; j++) {ans[j][n - i - 1] = a[i][j];}}swap(a, ans);}
};套路题，模拟
240. 搜索二维矩阵 II
class Solution {
public:bool searchMatrix(vector<vector<int>>& a, int target) {int n = a.size(), m = a[0].size();int x = 0, y = m - 1;while (x < n && y >= 0) {if (a[x][y] == target) return true;if (a[x][y] > target) y--;else x++;}return false;}
};Z字形查找
