题解 | #数组中未出现的最小正整数#

O(n),O(1)

    public int minNumberdisappered (int[] arr) {
        // write code here
        int minIdx = 0, n = arr.length;
        for (int i=0;i<n;i++){
            if (arr[i] > 0 && arr[i] <= n){
                arr[arr[i]-1] = arr[i];
                while (minIdx < n && arr[minIdx] == minIdx+1){
                    minIdx++;
                }
            }
        }
        return minIdx+1;
    }