public int firstMissingPositive(int[] nums) {

int l = 0;

int r = nums.length;

int temp;

while (l < r) {

//合法无需移位左边界加1

if (nums[l] == l + 1) {

l++;

} else if (nums[l] <= l || nums[l] > r || nums[nums[l] - 1] == nums[l]) {//非法右边界减1,三种情况：（1）小于等于l（2）大于等于r（3）重复值

nums[l]=nums[--r];

} else {//合法需移位，左右边界均不动

temp = nums[l];

nums[l] = nums[nums[l] - 1];

nums[temp - 1] = temp;

}

}

return l + 1;

}

public static void main(String[] args) {

FirstMissingPositive t = new FirstMissingPositive();

System.out.println();

}

}