[LeetCode] Search Insert Position，leetcodeinsert

[LeetCode] Search Insert Position，leetcodeinsert
題意: 給出一個target找出他在有序數組中的位置
思路1: 直接遍曆 複雜度O(N)
代碼1:

    public int searchInsert1(int[] A, int target) {//直接遍曆 演算法O(N)        int i = 0;        if(target < A[0]) return 0;        if(target > A[A.length - 1]) return A.length;        for(; i < A.length; ++ i){            if(A[i] == target) return i;            if(target < A[i+1] && target > A[i]) return i + 1;        }        return i;    }

思路2: 二分法,注意處理邊界問題,演算法複雜度 O(log(N))
代碼2:

    public int searchInsert(int[] A, int target) {//二分法 演算法O(log(N))        int i = 0;        if(target <= A[0]) return 0;        if(target > A[A.length - 1]) return A.length;        if(target == A[A.length - 1]) return A.length - 1;        int start = 0, end = A.length - 1, mid;        while (start < end){            mid = start + (end - start) / 2;            if(A[mid] < target){                start = mid + 1;            }else if(A[mid] > target){                end = mid -1;            }else {                return mid;            }        }        if(start >= end){            if(target > A[end]) {                return end + 1;            }            else if(target == A[end]) return end;            else {                return end;            }        }        return i;    }