主题：【原创】将24进行到底 -- 泰让

这是答应过面壁同学的c原码，因为周末在玩新买的电视，加上犯懒，所以晚了.

稍后将给出算法的解释.

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#include <string.h>

#define TAGET 24

#define NOP 4

#define EOP NOP*2-1

int comp[EOP];

double op[NOP];

int validate(void ){

int top=0;

double stack[NOP];

int i=0;

for (i=0;i<EOP;i++) {

if (comp[i]<=NOP) {

stack[top]=op[comp[i]-1];

top++;

} else {

switch (comp[i]-NOP) {

case 1:

top--;

stack[top-1]+=stack[top];

break;

case 2:

top--;

stack[top-1]-=stack[top];

break;

case 3:

top--;

stack[top-1]*=stack[top];

break;

case 4:

top--;

if (stack[top]==0)

return 0;

stack[top-1]/=stack[top];

break;

}

}

}

if (fabs(stack[0]-TAGET)<=1e-5)

return 1;

else

return 0;

}

void output(void ) {

int i;

int top=0;

char* stack[EOP];

char tempstr[255];

for (i=0;i<EOP;i++) {

stack[i]=malloc(255*sizeof(char));

}

for (i=0;i<EOP;i++) {

if (comp[i]<=NOP) {

sprintf(stack[top]," %d ",(int)op[comp[i]-1]);

top++;

} else {

switch (comp[i]-NOP) {

case 1:

top--;

sprintf(tempstr,"(%s+%s)",stack[top-1],stack[top]);

strcpy(stack[top-1],tempstr);

break;

case 2:

top--;

sprintf(tempstr,"(%s-%s)",stack[top-1],stack[top]);

strcpy(stack[top-1],tempstr);

break;

case 3:

top--;

sprintf(tempstr,"(%s*%s)",stack[top-1],stack[top]);

strcpy(stack[top-1],tempstr);

break;

case 4:

top--;

sprintf(tempstr,"(%s/%s)",stack[top-1],stack[top]);

strcpy(stack[top-1],tempstr);

break;

}

}

}

printf("%s\n",stack[0]);

for (i=0;i<EOP;i++) {

free(stack[i]);

}

}

int expandable(int i, int j){

int repeat=0;

int k;

if (j<=NOP) {

repeat=0;

for (k=0;k<=i-1;k++)

if (comp[k]==j) {

return 0;

}

}

int op=0;

int act=0;

for (k=0;k<=i-1;k++) {

if (comp[k]<=NOP)

op++;

else

act++;

if (op<act)

return 0;

}

return 1;

}

void expand(int i) {

int j;

if (i==EOP){

if (validate())

output();

}

else {

for (j=1;j<=NOP+4;j++) {

if (expandable(i+1,j)==1) {

comp[i]=j;

expand(i+1);

}

}

}

}

int main(int argc,char **argv) {

int a;

int i;

for (i=0;i<=(NOP-1);i++) {

scanf("%d",&a);

op[i]=a;

}

expand(0);

}

• 空循环会被编译器优化掉