leetcode 327. Count of Range Sum
2442 ワード
Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.
Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive.
Note:
A naive algorithm of O(n2) is trivial. You MUST do better than that.
Example:
Given nums = [-2, 5, -1], lower = -2, upper = 2,
Return 3.
The three ranges are : [0, 0], [2, 2], [0, 2] and their respective sums are: -2, -1, 2.
Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive.
Note:
A naive algorithm of O(n2) is trivial. You MUST do better than that.
Example:
Given nums = [-2, 5, -1], lower = -2, upper = 2,
Return 3.
The three ranges are : [0, 0], [2, 2], [0, 2] and their respective sums are: -2, -1, 2.
#include "stdafx.h"
#include<iostream>
//#include<vector>
//#include<algorithm>
using namespace std;
/*Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.
Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive.
Note:
A naive algorithm of O(n2) is trivial. You MUST do better than that.
Example:
Given nums = [-2, 5, -1], lower = -2, upper = 2,
Return 3.
The three ranges are : [0, 0], [2, 2], [0, 2] and their respective sums are: -2, -1, 2.*/
struct Check{
int lower;
int upper;
public:
Check(int l, int u){
lower = l;
upper = u;
}
Check(){}
bool in_range(int value)
{
return (value <= upper) && (value >= lower);
}
};
int count_num(int*begin,int*end,int lower, int upper)
{
int num = 0;
while (end != begin)
{
if (*begin >= lower&&*begin <= upper)
num++;
begin++;
}
return num;
}
int countRangeSum(int* nums, int numsSize, int lower, int upper)
{
int*sumarray = new int[numsSize];
memset(sumarray, 0, sizeof(int)*numsSize);
sumarray[0] = nums[0];
for (int i = 1; i < numsSize; i++)
{
sumarray[i] = sumarray[i - 1] + nums[i];
}
/*int countnum = count_if(sumarray, sumarray + numsSize, Check(lower, upper).in_range);
for (int i = 1; i < numsSize; i++)
{
Check check(lower + sumarray[i - 1], upper + sumarray[i - 1]);
countnum += count_if(sumarray + i, sumarray + numsSize, check.in_range);
}*/
int countnum = count_num(sumarray , sumarray + numsSize, lower, upper);;
for (int i = 1; i < numsSize; i++)
{
countnum += count_num(sumarray + i, sumarray + numsSize, lower + sumarray[i - 1], upper + sumarray[i - 1]);
}
delete[]sumarray;
return countnum;
}
int _tmain(int argc, _TCHAR* argv[])
{
int nums[3] = { -2, 5, -1 };
cout << countRangeSum(nums, 3, -2, 2);
system("pause");
return 0;
}