20230302 顺利通过
20230306 顺利通过
20230314 顺利通过
原题解
题目
约束
题解
解法一
class Solution {
public:
void sortColors(vector<int>& nums) {
int n = nums.size();
int ptr = 0;
for (int i = 0; i < n; ++i) {
if (nums[i] == 0) {
swap(nums[i], nums[ptr]);
++ptr;
}
}
for (int i = ptr; i < n; ++i) {
if (nums[i] == 1) {
swap(nums[i], nums[ptr]);
++ptr;
}
}
}
};
解法二
class Solution {
public:
void sortColors(vector<int>& nums) {
int n = nums.size();
int p0 = 0, p1 = 0;
for (int i = 0; i < n; ++i) {
if (nums[i] == 1) {
swap(nums[i], nums[p1]);
++p1;
} else if (nums[i] == 0) {
swap(nums[i], nums[p0]);
if (p0 < p1) {
swap(nums[i], nums[p1]);
}
++p0;
++p1;
}
}
}
};
解法三
class Solution {
public:
void sortColors(vector<int>& nums) {
int n = nums.size();
int p0 = 0, p2 = n - 1;
for (int i = 0; i <= p2; ++i) {
while (i <= p2 && nums[i] == 2) {
swap(nums[i], nums[p2]);
--p2;
}
if (nums[i] == 0) {
swap(nums[i], nums[p0]);
++p0;
}
}
}
};