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Leecode-c language implementation -15 Sum of three ----- ideas to be improved
2022-07-06 07:25:00 【Sunshine clover lxgzxj】
One 、 subject
Two 、 Their thinking
（1） Ideas need to be improved
For example, the array is ：{
-1,0,1,0,3}
（1） Construct a -10^5 To 10^5 Array of , Put the data one by one , Here for the convenience of writing -5 To 5.
（2） Define multiple variables to record the maximum and minimum subscripts and indexes when placing .
The number ：-5 -4 -3 -2 -1 0 1 2 3 4 5
frequency ： 0 0 0 0 1 1 1 0 1 0 0
Indexes ： 0 1 2 3 4 5 6 7 8 9 10
min max
temp
The length of the array ：11
MinIndex = 4
MaxIndex = 6
TempIndex = 4
MaxValue = 3
MinValue = -1
（3） If the minimum value is greater than zero , It means that no addition in the array can be 0, Returns a null value .
（4） If the maximum value is less than zero , It means that no addition in the array can be 0, Returns a null value .
（5） If twice the minimum plus the maximum is still greater than 0, It shows that this maximum value is definitely not in the final answer .
-1 * 2 + 3 > 0
MaxIndex Minus one
MaxIndex = 6
（5） If twice the maximum plus the minimum is still less than 0, It shows that this minimum value is definitely not in the final answer .
（6） Judgment logic ：MaxValue + MinValue + TempValue = 0, recorded TempIndex by 5 .
-1 + 1 + 0 = 0
（7） To determine TempIndex=5 The corresponding value is 1, Explain that there is only one in the array 0, And it does not coincide with the maximum and minimum values , Meet the requirements .
MaxIndex Minus one
MaxIndex = 6
Finally, add an array to the two-dimensional array ：{
{
-1 0 1 } }
（8） To determine ：
MinValue : -1 , MaxValue : 0 , TempValue : 1
Find out TempValue : 1 exceed MaxValue : 0, For repeating elements , Kicked out .
（9） To determine ：
MinValue : 0 , MaxValue : 1 , TempValue : -1
Find out TempValue : 1 exceed MinValue : 0, For repeating elements , Kicked out .
（10） To determine ：
MinValue : 0 , MaxValue : 0 , TempValue : 0
Find out 0 There are only two values , Here I took it three times , Kicked out .
3、 ... and 、VS Test code
（1） Ideas need to be improved
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ELEMENTSIZE 3
#define INITARRAYSIZE 10000
#define RECORDARRAYSIZE 10
void PrintfArr(void *arr, int size, int elementsize);
void PrintfHeadVal();
void Printf2DimensionArray(int** Array, int num1, int num2);
int** threeSum(int* nums, int numsSize, int* returnSize, int** returnColumnSizes);
int main()
{
int nums[] = {
-1,0,1,0,3 };
int numsSize = sizeof(nums) / sizeof(int);
int returnSize = 0;
int** returnColumnSizes = (int**)malloc(sizeof(int*));
PrintfArr(nums, numsSize, sizeof(int));
threeSum(nums, numsSize, &returnSize, returnColumnSizes);
return 0;
}
/* For example, the array is ： The number ：-5 -4 -3 -2 -1 0 1 2 3 4 5 frequency ： 0 1 2 1 3 1 0 2 4 5 1 Indexes ： 0 1 2 3 4 5 6 7 0 9 10 min max temp The length of the array ：11 （1） Construct a -10^5 To 10^5 Array of , Put the data one by one . （2） Define two variables to record the maximum and minimum subscripts when inserting . （3） If the minimum value is greater than zero , It means that no addition in the array can be 0, Returns a null value . （4） If the maximum value is less than zero , It means that no addition in the array can be 0, Returns a null value . （5） That is, there are three variables ,MaxIndex,MinIndex,TempIndex. （6） Judgment logic ：max Value + min Value + temp Value = 0, recorded . max Value + min Value + temp Value ！= 0, Don't record . （7）min <= 0, max >= 0, temp Value = 0 - min Value - max Value , To judge temp The index of the bit . （8）temp Whether the corresponding index bit is 0, If by 0, Don't record . by 1 You need to judge whether it is with max、min coincidence , Coincident exit , Non coincident records . Greater than, etc 2, Record . */
int** threeSum(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
*returnSize = 0;
if (numsSize < ELEMENTSIZE)
{
return NULL;
}
int** ResArray = (int**)malloc(sizeof(int*) * INITARRAYSIZE);
int* RecordArray = (int*)malloc(sizeof(int) * (RECORDARRAYSIZE * 2 + 1));
*returnColumnSizes = (int*)malloc(sizeof(int) * INITARRAYSIZE);
int MaxIndex = RECORDARRAYSIZE + nums[0];
int MinIndex = RECORDARRAYSIZE + nums[0];
int TempValue = 0;
int MaxValue = MaxIndex - RECORDARRAYSIZE;
int MinValue = MinIndex - RECORDARRAYSIZE;
int TempIndex = 0;
int i = 0;
int j = 0;
int Flag = 0;
// Initialize array RecordArray
for ( i = 0; i < RECORDARRAYSIZE * 2 + 1; i++)
{
RecordArray[i] = 0;
}
// take nums The values in the array are recorded in the array RecordArray in
// Record the maximum and minimum values and index
for ( i = 0; i < numsSize; i++)
{
MaxValue = MaxIndex - RECORDARRAYSIZE;
if (nums[i] > MaxValue)
{
MaxIndex = RECORDARRAYSIZE + nums[i];
}
MinValue = MinIndex - RECORDARRAYSIZE;
if(nums[i] < MinValue)
{
MinIndex = RECORDARRAYSIZE + nums[i];
}
RecordArray[RECORDARRAYSIZE + nums[i]]++;
}
MaxValue = MaxIndex - RECORDARRAYSIZE;
MinValue = MinIndex - RECORDARRAYSIZE;
PrintfHeadVal();
printf(" The number ：");
PrintfArr(RecordArray, RECORDARRAYSIZE * 2 + 1, sizeof(int));
printf("MaxIndex : %d , MaxValue : %d , MinIndex : %d , MinValue : %d\n", MaxIndex, MaxValue, MinIndex, MinValue);
// If the minimum value is greater than zero , It means that no addition in the array can be 0, Returns a null value .
// If the maximum value is less than zero , It means that no addition in the array can be 0, Returns a null value .
if (MaxValue < 0)
{
return NULL;
}
if (MinValue > 0)
{
return NULL;
}
// The following two cycles can reduce the following for Number of cycles , Speed up program efficiency .
// It's OK to , The efficiency is not improved .
while ((MinValue * 2 + MaxValue > 0) && (RecordArray[MaxIndex] != 0))
{
MaxIndex--;
MaxValue = MaxIndex - RECORDARRAYSIZE;
}
while ((MinValue + MaxValue * 2 < 0) && (RecordArray[MinIndex] != 0))
{
MinIndex++;
MinValue = MinIndex - RECORDARRAYSIZE;
}
for (i = MinIndex; i <= RECORDARRAYSIZE; i++)
{
if (RecordArray[i] == 0)
{
continue;
}
MinValue = i - RECORDARRAYSIZE;
while ((MinValue * 2 + MaxValue > 0) && (RecordArray[MaxIndex] != 0))
{
MaxIndex--;
MaxValue = MaxIndex - RECORDARRAYSIZE;
}
for ( j = MaxIndex; j >= RECORDARRAYSIZE; j--)
{
if (RecordArray[j] == 0)
{
continue;
}
MaxValue = j - RECORDARRAYSIZE;
TempValue = 0 - MinValue - MaxValue;
TempIndex = TempValue + RECORDARRAYSIZE;
printf(" i : %2d , MinValue : %2d ,j : %2d , MaxValue : %2d , TempIndex : %2d , TempValue : %2d , RecordArray[TempIndex] : %2d\n",
i, MinValue, j, MaxValue, TempIndex, TempValue, RecordArray[TempIndex]);
if (RecordArray[TempIndex] > 0)
{
if ((RecordArray[TempIndex] == 1) && (j > TempIndex) && (i < TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] == 2) && (j > TempIndex) && (i <= TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] == 2) && (j >= TempIndex) && (i < TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] > 2) && (j >= TempIndex) && (i <= TempIndex))
{
Flag = 1;
}
if (Flag)
{
printf("*returnSize : %d\n", *returnSize);
(*returnColumnSizes)[*returnSize] = ELEMENTSIZE;//*returnColumnSizes Put it in parentheses
ResArray[*returnSize] = (int*)malloc(sizeof(int) * ELEMENTSIZE);
ResArray[*returnSize][0] = MinValue;
ResArray[*returnSize][2] = MaxValue;
ResArray[*returnSize][1] = TempValue;
//printf("data : (%d , %d , %d)\n", ResArray[*returnSize][0], ResArray[*returnSize][2], ResArray[*returnSize][1]);
(*returnSize)++;
Printf2DimensionArray(ResArray, *returnSize, ELEMENTSIZE);
printf("+++++++++++++++++++++++++++++\n");
Flag = 0;
}
}
}
}
Printf2DimensionArray(ResArray, *returnSize, ELEMENTSIZE);
Printf2DimensionArray(returnColumnSizes, 1, *returnSize);
return ResArray;
}
void Printf2DimensionArray(int** Array, int num1, int num2)
{
int i, j;
printf("{");
for ( i = 0; i < num1; i++)
{
printf("{");
for ( j = 0; j < num2; j++)
{
printf("%2d ", Array[i][j]);
}
printf("} ");
}
printf("} \n");
}
void PrintfHeadVal()
{
int i;
printf(" Header ：");
for (i = -RECORDARRAYSIZE; i <= RECORDARRAYSIZE; i++)
{
printf("%3d ", i);
}
printf("\n");
printf(" Indexes ：");
for (i = 0; i <= RECORDARRAYSIZE * 2 ; i++)
{
printf("%3d ", i);
}
printf("\n");
}
void PrintfArr(void *arr, int size, int elementsize)
{
if (elementsize == sizeof(int))
{
int *tmparr = (int*)arr;
int i;
for (i = 0; i < size; i++)
{
printf("%3d ", tmparr[i]);
}
}
else if (elementsize == sizeof(char))
{
char *tmparr = (char*)arr;
int i;
for (i = 0; i < size; i++)
{
printf("%c ", tmparr[i]);
}
}
printf("\n========================\n");
}
Four 、VS Running results
5、 ... and 、leecode Submission code
#define ELEMENTSIZE 3
#define INITARRAYSIZE 20000
#define RECORDARRAYSIZE 100000
int** threeSum(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
*returnSize = 0;
if (numsSize < ELEMENTSIZE)
{
return NULL;
}
int** ResArray = (int**)malloc(sizeof(int*) * INITARRAYSIZE);
int* RecordArray = (int*)malloc(sizeof(int) * (RECORDARRAYSIZE * 2 + 1));
*returnColumnSizes = (int*)malloc(sizeof(int) * INITARRAYSIZE);
int MaxIndex = RECORDARRAYSIZE + nums[0];
int MinIndex = RECORDARRAYSIZE + nums[0];
int TempValue = 0;
int MaxValue = MaxIndex - RECORDARRAYSIZE;
int MinValue = MinIndex - RECORDARRAYSIZE;
int TempIndex = 0;
int i = 0;
int j = 0;
int Flag = 0;
for ( i = 0; i < RECORDARRAYSIZE * 2 + 1; i++)
{
RecordArray[i] = 0;
}
for ( i = 0; i < numsSize; i++)
{
MaxValue = MaxIndex - RECORDARRAYSIZE;
if (nums[i] > MaxValue)
{
MaxIndex = RECORDARRAYSIZE + nums[i];
}
MinValue = MinIndex - RECORDARRAYSIZE;
if(nums[i] < MinValue)
{
MinIndex = RECORDARRAYSIZE + nums[i];
}
RecordArray[RECORDARRAYSIZE + nums[i]]++;
}
MaxValue = MaxIndex - RECORDARRAYSIZE;
MinValue = MinIndex - RECORDARRAYSIZE;
if (MaxValue < 0)
{
return NULL;
}
if (MinValue > 0)
{
return NULL;
}
while ((MinValue * 2 + MaxValue > 0) && (RecordArray[MaxIndex] != 0))
{
MaxIndex--;
MaxValue = MaxIndex - RECORDARRAYSIZE;
}
while ((MinValue + MaxValue * 2 < 0) && (RecordArray[MinIndex] != 0))
{
MinIndex++;
MinValue = MinIndex - RECORDARRAYSIZE;
}
for (i = MinIndex; i <= RECORDARRAYSIZE; i++)
{
if (RecordArray[i] == 0)
{
continue;
}
MinValue = i - RECORDARRAYSIZE;
while ((MinValue * 2 + MaxValue > 0) && (RecordArray[MaxIndex] != 0))
{
MaxIndex--;
MaxValue = MaxIndex - RECORDARRAYSIZE;
}
for ( j = MaxIndex; j >= RECORDARRAYSIZE; j--)
{
if (RecordArray[j] == 0)
{
continue;
}
MaxValue = j - RECORDARRAYSIZE;
TempValue = 0 - MinValue - MaxValue;
TempIndex = TempValue + RECORDARRAYSIZE;
if (RecordArray[TempIndex] > 0)
{
if ((RecordArray[TempIndex] == 1) && (j > TempIndex) && (i < TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] == 2) && (j > TempIndex) && (i <= TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] == 2) && (j >= TempIndex) && (i < TempIndex))
{
Flag = 1;
}
else if ((RecordArray[TempIndex] > 2) && (j >= TempIndex) && (i <= TempIndex))
{
Flag = 1;
}
if (Flag)
{
(*returnColumnSizes)[*returnSize] = ELEMENTSIZE;
ResArray[*returnSize] = (int*)malloc(sizeof(int) * ELEMENTSIZE);
ResArray[*returnSize][0] = MinValue;
ResArray[*returnSize][2] = MaxValue;
ResArray[*returnSize][1] = TempValue;
(*returnSize)++;
Flag = 0;
}
}
}
}
return ResArray;
}
6、 ... and 、 Running results
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