Array in-place operation link1
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16class Solution {
public int firstMissingPositive(int[] nums) {
int n = nums.length;
for (int i = 0; i < n; i++) {
while (nums[i] > 0 && nums[i] <= n && nums[nums[i] - 1] != nums[i]) {
int next = nums[nums[i] - 1];
nums[nums[i] - 1] = nums[i];
nums[i] = next;
}
}
for (int i = 0; i < nums.length; i++) {
if (nums[i] != i + 1) return i+1;
}
return nums.length + 1;
}
}