LeetCode开心刷题十八天——34. Find First and Last Position of Element in Sorted Array（Easy）35. Search Insert Position(Easy)36. Valid Sudoku

ATTENTION:only thing need to pay attention is the loop condition is left<=right,don;t forget =

PROBLEM：my code is long,there must some easier way to design it

34. Find First and Last Position of Element in Sorted Array

Medium

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Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

Example 1:

Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]

Example 2:

Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]

Answer Code:

#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<stack>
#include<string>

using namespace std;
class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        int n=nums.size();
        cout<<"n:"<<n<<endl;
        vector<int> res;
        if(n==1)
        {
            if(target==nums[0])
            {
                res.push_back(0);
                res.push_back(0);
                return res;
            }
            else
            {
                res.push_back(-1);
                res.push_back(-1);
                return res;
            }
        }
        int left=0,right=n-1;
        int flag=0,mid=0;
        while(left<=right)
        {
            mid=(left+right)/2;
            cout<<"mid:"<<mid<<endl;
            if(nums[mid]==target)
            {
                flag=1;
                break;
            }
            if(nums[mid]>target)
            {
                right=mid-1;
            }
            else if(nums[mid]<target)
            {
                left=mid+1;
                //cout<<"left:"<<left<<endl;
            }
        }
        if(flag==0)
        {
            res.push_back(-1);
            res.push_back(-1);
            return res;
        }
        else if(flag==1)
        {
            int temp=mid,temp1=mid;
            //cout<<"mid:"<<mid<<endl;
            cout<<"n:"<<n<<endl;
            while(temp>0&&nums[temp]==nums[temp-1])
            {
                temp--;
            }
            while(temp1<n-1&&nums[temp1]==nums[temp1+1])
            {
                temp1++;
            }
            res.push_back(temp);
            res.push_back(temp1);
        }
        return res;
    }
};
int main()
{
    int target=4;
    vector<int> a,res;
    a.push_back(1);
    a.push_back(4);
 //   a.push_back(2);
//    a.push_back(8);
//    a.push_back(8);
//    a.push_back(10);
    Solution s;
    res=s.searchRange(a,target);
    for(auto t:res)
    {
        cout<<t<<endl;
    }
    return 0;
}

 

35. Search Insert Position

Easy

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Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Example 1:

Input: [1,3,5,6], 5
Output: 2

Example 2:

Input: [1,3,5,6], 2
Output: 1

Example 3:

Input: [1,3,5,6], 7
Output: 4

Example 4:

Input: [1,3,5,6], 0
Output: 0

Accepted

423,275

Submissions

1,031,994

 

attention:The only point is to establish the awareness of memory management,when  you traversal vector or other containers.You need to think whether this subscript will cause overflow.

#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<stack>
#include<string>

using namespace std;
class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        int n=nums.size(),res=0;
        if(nums[n-1]<target) return n;
        while(nums[res]<=target&&res<n-1)
        {
            if(nums[res]==target) return res;
            res++;
        }
        return res;
    }
};
int main()
{
    int target=7,res=0;
    vector<int> a;
    a.push_back(1);
    a.push_back(3);
    a.push_back(5);
    a.push_back(6);
//    a.push_back(8);
//    a.push_back(10);
    Solution s;
    res=s.searchInsert(a,target);
    cout<<res<<endl;
    return 0;
}

36. Valid Sudoku

Medium

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Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

1. Each row must contain the digits 1-9 without repetition.
2. Each column must contain the digits 1-9 without repetition.
3. Each of the 9 3x3 sub-boxes of the grid must contain the digits 1-9 without repetition.

A partially filled sudoku which is valid.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

Example 1:

Input:
[
  ["5","3",".",".","7",".",".",".","."],
  ["6",".",".","1","9","5",".",".","."],
  [".","9","8",".",".",".",".","6","."],
  ["8",".",".",".","6",".",".",".","3"],
  ["4",".",".","8",".","3",".",".","1"],
  ["7",".",".",".","2",".",".",".","6"],
  [".","6",".",".",".",".","2","8","."],
  [".",".",".","4","1","9",".",".","5"],
  [".",".",".",".","8",".",".","7","9"]
]
Output: true

Example 2:

Input:
[
  ["8","3",".",".","7",".",".",".","."],
  ["6",".",".","1","9","5",".",".","."],
  [".","9","8",".",".",".",".","6","."],
  ["8",".",".",".","6",".",".",".","3"],
  ["4",".",".","8",".","3",".",".","1"],
  ["7",".",".",".","2",".",".",".","6"],
  [".","6",".",".",".",".","2","8","."],
  [".",".",".","4","1","9",".",".","5"],
  [".",".",".",".","8",".",".","7","9"]
]
Output: false
Explanation: Same as Example 1, except with the 5 in the top left corner being 
    modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
ATTENTION：
The most important code is memset(map,0,sizeof(map));
I use this to reset the map array at right place.
Only in the right place ,can we make it right.
Especially,when we loop column and 3*3,this code need to be different place.
The judge way is to determine when to start a new count

#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<stack>
#include<string>
#include<memory>
#include<memory.h>
using namespace std;
class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        if(board.size()!=9||board[0].size()!=9) return false;
        int map[10]={0},num=0;
        for(int i=0;i<9;i++)
        {
            memset(map,0,sizeof(map));
            for(int j=0;j<9;j++)
            {
                if(board[i][j]=='.') continue;
                if(board[i][j]>='0'&&board[i][j]<='9')
                {
                    num=board[i][j]-'0';
                }
                if(map[num]==0)
                {
                    map[num]++;
                }
                else
                {
                    return false;
                }

            }
        }
        for(int j=0;j<9;j++)
        {
            memset(map,0,sizeof(map));
            for(int i=0;i<9;i++)
            {
                if(board[i][j]=='.') continue;
                if(board[i][j]>='0'&&board[i][j]<='9')
                {
                    num=board[i][j]-'0';
                }
                if(map[num]==0)
                {
                    map[num]=1;
                }
                else
                {
                    return false;
                }

            }
        }
        for(int i=0;i<9;i+=3)
        {
            for(int j=0;j<9;j+=3)
            {
                int k=i+3,p=j+3;
                memset(map,0,sizeof(map));
                for(int t=i;t<k;t++)
                {
                    for(int l=j;l<p;l++)
                    {
                        if(board[t][l]=='.') continue;
                        if(board[t][l]>='0'&&board[t][l]<='9')
                        {
                            num=board[t][l]-'0';
                        }
                        if(map[num]==0)
                        {
                            map[num]++;
                        }
                        else
                        {
                            return false;
                        }
                    }
                }

            }
        }
        return true;
    }
};
int main()
{
    bool res=0;
//    a.push_back(8);
//    a.push_back(10);
    vector<vector<char>> board={
    {'.','.','4','.','.','.','6','3','.'},
    {'.','.','.','.','.','.','.','.','.'},
    {'5','.','.','.','.','.','.','9','.'},
    {'.','.','.','5','6','.','.','.','.'},
    {'4','.','3','.','.','.','.','.','1'},
    {'.','.','.','7','.','.','.','.','.'},
    {'.','.','.','5','.','.','.','.','.'},
    {'.','.','.','.','.','.','.','.','.'},
    {'.','.','.','.','.','.','.','.','.'}
    };
    Solution s;
    res=s.isValidSudoku(board);
    cout<<res<<endl;
    return 0;
}