directory

Problem 1: Search for insertion location

Problem 2: Appearance arrays

Problem 3: maximum suborder sum

Problem 4: The length of the last word

Problem 5: Add one

Problem 6: binary summation

Problem 7: Find the square root

Problem 8: Climb the stairs

Delete duplicate elements from sorted lists

Merge two ordered arrays

LeetCode brushes the questions regularly, with 10 questions in each period. Comrades with heavy business can look at the ideas I share, which are not the most efficient solutions, but for mutual improvement.

Question 1:Search for insertion position

The requirements are as follows:

Answer (C language) :

int searchInsert(int* nums, int numsSize, int target){
    int num=0;

    if(numsSize<=0)
        return 0;

    for(int i=0,j=1; i<numsSize; i++,j++){if(target<nums[0]){
            num=0;
            break;
        }
        else if(target>nums[numsSize- 1]){
            num=numsSize;
            break;
        }
        else{
            if(nums[i]==target) {
                num=i; 
                break;
            }
            if(target>nums[i] && target<nums[j]){
                num=j; 
                break; }}}return num;
}
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Question 2:Appearance of the array

The requirements are as follows:

Answer (C language) :

char * countAndSay(int n){
    
    if(n==1) 
        return "1";
    
    char *s=countAndSay(n- 1);

    char *a=(char *)malloc(5000);
    char *ans=(char *)malloc(5000);

    int count=0;
    int l=strlen(s);
    int j=0;
    for(int i=0; i<l; i++){if(i == 0 || s[i]==s[i- 1])
            count++;
        else{
            a[j++]='0'+count;
            a[j++]=s[i- 1];
            count=1;
        }
        if (i == l - 1) {
            a[j++]='0'+count;
            a[j++]=s[i];
        }
    }
    
    a[j]='\ 0';
    ans = a;
    return ans;
}
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Question 3:Maximum suborder sum

The requirements are as follows:

Answer (C language) :

int maxSubArray(int* nums, int numsSize){
  int max = nums[0];
  int b = 0;
  for(int i = 0; i < numsSize; i++){
    b += nums[i];
    if(b > max) max = b;
    if(b < 0) b = 0;
  }
  return max;
}
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Problem 4: The length of the last word

The requirements are as follows:

Answer (C language) :

int lengthOfLastWord(char * s){  
    int num=strlen(s); 
    int len=0;

    if(num<=0)
        return 0;

    // if there is a space, remove the space
    // Return 0 if all Spaces are blank
    while(s[--num]==' ') {if(num==0) {return 0; }}while(num>=0) {if(s[num--]==' ')
            break;
        len++;
    }   

    return len;
}
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Problem 5: Add one

The requirements are as follows:

Answer (C language) :

int* plusOne(int* digits, int digitsSize, int* returnSize){
    
    int *buf=(int *)malloc((digitsSize + 1) * sizeof (int));

    for(int i=digitsSize- 1; i>=0; i--){if(digits[i]+1= =10){
            digits[i]=0;
        }
        else{
            digits[i]+=1;
            returnSize[0]=digitsSize;
            return digits;
        }
    }
    
    buf[0] =1;
    for(int i=0,j=1; i<digitsSize; i++,j++) buf[j]=digits[i]; returnSize[0]=digitsSize+1;
    return buf;
}
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Problem 6: binary summation

The requirements are as follows:

Answer (C language) :

char * addBinary(char * a, char * b){
    int num=0,len_a=strlen(a),len_b=strlen(b),len_long=0;

    if(len_a>=len_b){
        len_long=len_a+2;
    }
    else{
        len_long=len_b+2;
    }

    char *buf=(char *)malloc(sizeof(char)*(len_long)) ;
    buf[--len_long]='\ 0';
    buf[0] ='0';

    while(len_long>0){
        num+=len_a>0? a[--len_a]-'0':0;
        num+=len_b>0? b[--len_b]-'0':0;

        if(num==0){
            num=0;
            buf[--len_long]='0';
        }
        else if(num==1){
            num=0;
            buf[--len_long]='1';
        }
        else if(num==2){
            num=1;
            buf[--len_long]='0';
        }
        else if(num==3){
            num=1;
            buf[--len_long]='1'; }}if(buf[0] = ='0')
        return buf+1;
    else    
        return buf;
}
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Problem 7: Find the square root

The requirements are as follows:

Answer (C language) :

int mySqrt(int x){
    // Newton iterative method
    long r = x;
	while(r * r > x)
	{
		r = (r + x / r) / 2;/ / iteration
	}
	return (int)r;
}
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Problem 8: Climb the stairs

The requirements are as follows:

Answer (C language), algorithm description:

int climbStairs(int n){
    if (n == 1) {
        return 1;
    }
    int *dp=(int *)malloc(sizeof(int)*(n+1));
    dp[1] = 1;
    dp[2] = 2;

    for (int i = 3; i <= n; i++) {
        dp[i] = dp[i - 1] + dp[i - 2];
    }
    
    return dp[n];
}
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Delete duplicate elements from sorted lists

The requirements are as follows:

Answer (C language) :

/** * Definition for singly-linked list. * struct ListNode { * int val; * struct ListNode *next; *}; * /

struct ListNode* deleteDuplicates(struct ListNode* head){
    struct ListNode * p = head;
    struct ListNode * q;
    
    while(NULL! = p) {while(NULL! = p->next && p->val == p->next->val) { q = p->next; p->next = q->next;free(q);
        }
        p = p->next;
    }
    return head;
}
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Merge two ordered arrays

The requirements are as follows:

Answer (C language) :

void merge(int* nums1, int nums1Size, int m, int* nums2, int nums2Size, int n){
    int p = m + n;
    m--;
    n--;

    while (n >= 0 && m >= 0) {
        nums1[--p] = nums1[m] <= nums2[n] ? nums2[n--] : nums1[m--];
    }
    
    while (n >= 0) { nums1[--p] = nums2[n--]; }}Copy the code