-
Notifications
You must be signed in to change notification settings - Fork 0
/
first-missing-positive.cc
38 lines (37 loc) · 1.11 KB
/
first-missing-positive.cc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
class Solution {
public:
// use nums in place so that: nums[i] == i + 1
// not nums[i] == i because nums[0] should be 1 ..
int firstMissingPositive(vector<int>& nums) {
int len = nums.size();
for(int i = 0; i < len; i++) {
if (nums[i] < 0) {
continue;
} else if (nums[i] == i + 1) {
continue;
} else {
if (nums[i] > len) {
nums[i] = -1;
} else {
while(nums[i] > 0 && nums[i] <= len) {
int tmp = nums[nums[i] - 1];
if (tmp == nums[i]) {
break;
}
nums[nums[i] - 1] = nums[i];
nums[i] = tmp;
}
if (nums[i] > len) {
nums[i] = -1;
}
}
}
}
for(int i = 0; i < len; i++) {
if (nums[i] != i + 1) {
return i + 1;
}
}
return len + 1;
}
};