puzzle10.c

/*
 *-- puzzle10.c --
 * 2015/05/15(fri)
 * walkingmask
 * 任意の4つの数字(かぶり無し)と3つの演算子(かぶり有り)で10を作れるか(10パズル)
 * 組み合わせの数は 4! * 4^3 = 24 * 64 1536通り
 *-- 問題点 -- 
 * 1 1 5 8 のような 8/(1-1/5)=10 括弧を使った計算を考慮してない
 * 解決策としては，部分和同士の演算も書くことが挙げられる
 * n1*n2*n3*n4 , (n1*n2)*n3*n4 , (n1*n2)*n3)*n4 , (n1*n2)*(n3*n4)
 * n1*(n2*n3*n4) , n1*n2*n3*n4 ...
 *-- 実行例 --
 %./puzzle10
 input 1st number => 1
 input 2st number => 2
 input 3st number => 2
 input 4st number => 4
 1 : 1.000000 + 2.000000 + 2.000000 + 4.000000 = 9.000000
 2 : 1.000000 - 2.000000 + 2.000000 + 4.000000 = 5.000000
 3 : 1.000000 * 2.000000 + 2.000000 + 4.000000 = 8.000000
 4 : 1.000000 / 2.000000 + 2.000000 + 4.000000 = 6.500000
 5 : 1.000000 + 2.000000 - 2.000000 + 4.000000 = 5.000000
 6 : 1.000000 - 2.000000 - 2.000000 + 4.000000 = 1.000000
 7 : 1.000000 * 2.000000 - 2.000000 + 4.000000 = 4.000000
 8 : 1.000000 / 2.000000 - 2.000000 + 4.000000 = 2.500000
 9 : 1.000000 + 2.000000 * 2.000000 + 4.000000 = 10.000000
 true
 */

#include <stdio.h>

void f(int *array);

int main(){
	int e_nums[6][4] = {{0,1,2,3},{0,1,3,2},{0,2,1,3},{0,2,3,1},{0,3,1,2},{0,3,2,1}};
	int ope[3] = {0,0,0};
	int i,j,k,p=1;

	float sum;
	float in_nums[4];
	for(i=0;i<4;i++){
		printf("input %dst number => ", i+1);scanf("%f", &in_nums[i]);
	}

	for(i=0;i<6;i++){
		for(j=0;j<4;j++){
			while(ope[2] < 4){
				sum = in_nums[e_nums[i][0]];

				printf("%d : %f ", p, sum); // debug

				for(k=0;k<3;k++){
					switch(ope[k]){
						case 0:
							sum += in_nums[e_nums[i][k+1]];
							printf("+ "); // debug
							break;
						case 1:
							sum -= in_nums[e_nums[i][k+1]];
							printf("- "); // debug
							break;
						case 2:
							sum *= in_nums[e_nums[i][k+1]];
							printf("* "); // debug
							break;
						case 3:
							if(in_nums[e_nums[i][k+1]] != 0){
								sum /= in_nums[e_nums[i][k+1]];
								printf("/ "); // debug
							}else{
								sum += 0;
								printf("+ "); // debug
							}
							break;
					}
					printf("%f ", in_nums[e_nums[i][k+1]]); // debug
				}
				printf("= %f\n", sum); // debug
				if(sum == 10){
					printf("true\n");
					return 0;
				}
				ope[0] += 1;
				if(ope[0] == 4){
				ope[0] = 0;
				ope[1] += 1;
				}
				if(ope[1] == 4){
				ope[1] = 0;
				ope[2] += 1;
				}
				p++;
			}
			for(k=0;k<3;k++)ope[k]=0;
			f(e_nums[i]);
		}
	}
	printf("false\n");
	return 0;
}

void f(int *array){
	int temp = array[0];
	array[0] = array[1];
	array[1] = array[2];
	array[2] = array[3];
	array[3] = temp;
}