123456789這九個按順序排列的數，要求在它們之間插入若干個+，-，*，/ ，使其結果正好等於100如 ： 1*2*3*4+5+6+7*8+9=100。c++一解

 #include<iostream>

using std::cout;

using std::endl;

enum op

{

pplus, sub, mul, div

};

int method = 1;

int num = 1;

float temS;

op o[9];

void outPut()

{

cout << "Method:" << method++ << endl;

for (int i = 0; i < 8; i++)

{

cout << i + 1;

switch (o[i])

{

case pplus:

cout << "+";

break;

case sub:

cout << "-";

break;

case mul:

cout << "*";

break;

case div:

cout << "/";

break;

}

}

cout << "9=100" << endl;

}

float calculate(float n, op oper, float sum)

{

switch (oper)

{

case pplus:

return n + sum;

case sub:

return n - sum;

case mul:

return n * sum;

case div:

return n / sum;

}

}

void result(float nowSum, float stackN, op stackO)

{

float sum = nowSum;

op oper;

num++;

if (num > 9)

{

sum = calculate(stackN, stackO, sum);

if (sum - 100 < 0.001 && sum - 100 > -0.001)

outPut();

num--;

return;

}

// +

o[num - 2] = pplus;

temS = stackN;

oper = stackO;

sum = calculate(temS, oper, sum);

temS = sum;

sum = num;

result(sum, temS, pplus);

// -

o[num - 2] = sub;

sum = nowSum;

temS = stackN;

oper = stackO;

sum = calculate(temS, oper, sum);

temS = sum;

sum = num;

result(sum, temS, sub);

// *

sum = nowSum;

o[num - 2] = mul;

sum *= num;

result(sum, stackN, stackO);

// /

sum = nowSum;

o[num - 2] = div;

sum /= num;

result(sum, stackN, stackO);

num--;

}

int main()

{

float sum = 1.0, store = 0.0;

result(sum, store, pplus);

return 0;

}