C++代码:计算使两个数组相同所需的操作次数
假设我们有两个包含n个元素的数组A和B。考虑一个操作:选择两个索引i和j,然后将第i个元素减少1,并将第j个元素增加1。执行操作后,数组的每个元素必须是非负的。我们想要使A和B相同。我们必须找到使A和B相同的操作序列。如果不可能,则返回-1。
因此,如果输入类似于A = [1, 2, 3, 4];B = [3, 1, 2, 4],则输出将为[(1, 0), (2, 0)],因为对于i = 1和j = 0,数组将为[2, 1, 3, 4],然后对于i = 2和j = 0,它将为[3, 1, 2, 4]
步骤
为了解决这个问题,我们将遵循以下步骤:
a := 0, b := 0, c := 0 n := size of A Define an array C of size n and fill with 0 for initialize i := 0, when i < n, update (increase i by 1), do: a := a + A[i] for initialize i := 0, when i < n, update (increase i by 1), do: b := b + A[i] if a is not equal to b, then: return -1 Otherwise for initialize i := 0, when i < n, update (increase i by 1), do: c := c + |A[i] - B[i]| C[i] := A[i] - B[i] c := c / 2 i := 0 j := 0 while c is non-zero, decrease c after each iteration, do: while C[i] <= 0, do: (increase i by 1) while C[j] >= 0, do: (increase j by 1) print i and j decrease C[i] and increase C[j] by 1
示例
让我们来看下面的实现以更好地理解:
#include <bits/stdc++.h>
using namespace std;
void solve(vector<int> A, vector<int> B){
int a = 0, b = 0, c = 0;
int n = A.size();
vector<int> C(n, 0);
for (int i = 0; i < n; i++)
a += A[i];
for (int i = 0; i < n; i++)
b += A[i];
if (a != b){
cout << -1;
return;
}
else{
for (int i = 0; i < n; i++){
c += abs(A[i] - B[i]);
C[i] = A[i] - B[i];
}
c = c / 2;
int i = 0, j = 0;
while (c--){
while (C[i] <= 0)
i++;
while (C[j] >= 0)
j++;
cout << "(" << i << ", " << j << "), ";
C[i]--, C[j]++;
}
}
}
int main(){
vector<int> A = { 1, 2, 3, 4 };
vector<int> B = { 3, 1, 2, 4 };
solve(A, B);
}输入
{ 1, 2, 3, 4 }, { 3, 1, 2, 4 }输出
(1, 0), (2, 0),
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