九日集训第三天

搜索旋转排序数组

搜索旋转排序数组||

寻找旋转排序中的数组最小值

爬楼梯

搜索旋转排序数组

cpp 复制代码

class Solution {
public:
    int search(vector<int>& nums, int target) {
        for(int i=0;i<nums.size();i++){
            if(nums[i]==target)return i;
        }
        return -1;
    }
};

搜索旋转排序数组||

cpp 复制代码

class Solution {
public:
    bool search(vector<int>& nums, int target) {
        for(int i=0;i<nums.size();i++){
            if(nums[i]==target)return true;
        }
        return false;
    }
};

寻找旋转排序中的数组最小值

cpp 复制代码

class Solution {
public:
    int findMin(vector<int>& nums) {
        int res=INT_MAX;
        for(int i=0;i<nums.size();i++){
            res=min(res,nums[i]);
        }
        return res;
    }
};

爬楼梯

cpp 复制代码

class Solution {
public:
    int climbStairs(int n) {
        if(n<=3)return n;
        int a=1;
        int b=2;
        for(int i=3;i<=n;i++){
            int t=a+b;
            a=b;
            b=t;
        }
        return b;
    }
};

斐波那契数

cpp 复制代码

class Solution {
public:
    int fib(int n) {
        if(n<=1)return n;
        int a=0;
        int b=1;
        for(int i=2;i<=n;i++){
            int t=a+b;
            a=b;
            b=t;
        }
        return b;
    }
};

第N个泰波那契数

cpp 复制代码

class Solution {
public:
    int tribonacci(int n) {
        if(n==0)return 0;
        if(n==1)return 1;
        if(n==2)return 1;
        int a=0;
        int b=1;
        int c=1;
        for(int i=3;i<=n;i++){
            int C=a+b+c;
            int B=c;
            int A=b;
            a=A;
            b=B;
            c=C;
        }
        return c;
    }
};

差的绝对值为K的数对数目

cpp 复制代码

class Solution {
public:
    int countKDifference(vector<int>& nums, int k) {
        int res=0;
        for(int i=0;i<nums.size();i++){
            for(int j=i+1;j<nums.size();j++){
                if(abs(nums[i]-nums[j])==k)res++;
            }
        }
        return res;
    }
};

猜数字

cpp 复制代码

class Solution {
public:
    int game(vector<int>& guess, vector<int>& answer) {
        int res=0;
        for(int i=0;i<3;i++){
            if(guess[i]==answer[i])res++;
        }
        return res;
    }
};

拿硬币

cpp 复制代码

class Solution {
public:
    int minCount(vector<int>& coins) {
        int res=0;
        for(int i=0;i<coins.size();i++){
            if(coins[i]%2==1){
                res++;
                coins[i]--;
            }
            res+=coins[i]/2;
        }
        return res;
    }
};

山峰数组的峰顶索引

cpp 复制代码

class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {
        int left=1;
        int right=arr.size()-2;
        int res=0;
        while(left<=right){
            int mid=left+((right-left)>>1);
            if(arr[mid]<arr[mid+1]){
                left=mid+1;
            }
            else if(arr[mid]>arr[mid+1]){
                right=mid-1;
                res=mid;
            }
            
        }
        return res;
    }
};