98 lines
2.1 KiB
C
98 lines
2.1 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#define N 20
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int nb_num;
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int tab[N];
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int stack_ptr;
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int stack_op[N];
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int stack_res[60];
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int result;
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int find(int n, int i1, int a, int b, int op)
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{
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int i, j;
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int c;
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if (stack_ptr >= 0) {
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stack_res[3*stack_ptr] = a;
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stack_op[stack_ptr] = op;
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stack_res[3*stack_ptr+1] = b;
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stack_res[3*stack_ptr+2] = n;
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if (n == result)
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return 1;
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tab[i1] = n;
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}
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for(i=0;i<nb_num;i++) {
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for(j=i+1;j<nb_num;j++) {
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a = tab[i];
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b = tab[j];
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if (a != 0 && b != 0) {
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tab[j] = 0;
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stack_ptr++;
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if (find(a + b, i, a, b, '+'))
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return 1;
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if (find(a - b, i, a, b, '-'))
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return 1;
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if (find(b - a, i, b, a, '-'))
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return 1;
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if (find(a * b, i, a, b, '*'))
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return 1;
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if (b != 0) {
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c = a / b;
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if (find(c, i, a, b, '/'))
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return 1;
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}
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if (a != 0) {
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c = b / a;
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if (find(c, i, b, a, '/'))
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return 1;
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}
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stack_ptr--;
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tab[i] = a;
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tab[j] = b;
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}
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}
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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int i, res, p;
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if (argc < 3) {
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printf("usage: %s: result numbers...\n"
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"Try to find result from numbers with the 4 basic operations.\n", argv[0]);
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exit(1);
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}
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p = 1;
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result = atoi(argv[p]);
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printf("result=%d\n", result);
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nb_num = 0;
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for(i=p+1;i<argc;i++) {
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tab[nb_num++] = atoi(argv[i]);
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}
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stack_ptr = -1;
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res = find(0, 0, 0, 0, ' ');
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if (res) {
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for(i=0;i<=stack_ptr;i++) {
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printf("%d %c %d = %d\n",
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stack_res[3*i], stack_op[i],
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stack_res[3*i+1], stack_res[3*i+2]);
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}
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return 0;
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} else {
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printf("Impossible\n");
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return 1;
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}
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}
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