背包问题的非递归解法

老师写的太乱了，真是看晕了，改天再看。

 

#include "stdio.h"#define LEN 5#define S0 10#define N0 5typedef struct { int s; int n; int job;} KNAPTP ;int w[LEN+1] = {0,1,4,4,5,7};KNAPTP stack[100];int top;/*===================*/void ps(){ int i; for (i=top; i>=1; i--) printf("%d %d %d/n",stack[i].s, stack[i].n, stack[i].job); printf("=======/n");}/*===================*/int knap(int s, int n){ KNAPTP x; int k; /* 布置初始任务 */ x.s = s; x.n = n; x.job = 0; top = 1; stack[top] = x; /* push */ k = 0; while ( (top >= 1) && !k ) { /* 取得一项任务 */ x = stack[top]; /* 对栈顶任务递推求解 */ while ( !k ) { if ( x.s == 0 ) k = 1 ; else if ( x.s<0 || x.n<=0 ) break; else { /* 布置下层包含w[n]重量的任务 job=1 */ x.s = x.s-w[x.n]; x.n--; x.job = 1; stack[++top] = x; /* push */ } }// printf("-- test1 --/n"); ps(); (void)getchar(); if ( !k ) {while ( ( top >= 1 ) ) {x = stack[top--]; /* pop */if ( x.job == 1 ) {/* 布置本层不包含w[n]重量的任务 */x.s += w[x.n+1]; x.job = 2;stack[++top] = x; /* push */break;}}// printf("-- test2 --/n"); ps(); (void)getchar(); } } /* 求解结果的处理 */ if ( k ) { while ( top >= 1 ) { x = stack[top--]; /* pop */ if (x.job ==1 ) printf("%d ", w[x.n+1] ); } } return (k);}/*===================*/main() {if ( knap(S0,N0) ) printf("此'背包问题'有解!/n");else printf("此'背包问题'无解!/n");}. 

 

 

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老师写的好像有错误，下面是我写的，大概摸清了意思,注意看注释

 

// 简单背包的非递归算法#include <stdio.h>#define MAX_ARRAY 0xff#define LEN 5#define S0 10#define N0 5typedef struct _workState {int s,n,isPushed;}workState;int w[LEN+1] = {0,1,4,4,5,7};workState myWork[MAX_ARRAY] = {0};int TOP=0;int knap(int s, int n) {int isOK = 0; // 成功标志workState ini_workState;ini_workState.isPushed = 0;ini_workState.n = n;ini_workState.s = s;myWork[TOP++] = ini_workState; // Push the initial state in stackwhile (TOP>0 && !isOK) // if there are some states in stack{// take the TOP stateini_workState = myWork[--TOP];while (TOP>0 && !isOK){if(ini_workState.s == 0) isOK = 1;else if(ini_workState.n < 0 || ini_workState.s < 0) { isOK=0; break; } // 如果当前状态不成功，那么就会跳出来else {ini_workState.isPushed = 1; // 表示当前状态是成功路径ini_workState.s -= w[ini_workState.n];--ini_workState.n;myWork[TOP++] = ini_workState; // Push the new state in stack}}//////////////////////////////////////////////////////////////////////////// 这种情况是当前状态的修改，即去掉一个当前状态，所以不用ini_workState.n 做++或--if(!isOK) {while (TOP>0){// 这种情况下可以出栈，先出栈修改才能进栈，但是如果为零的结点全出栈了，好像也不会有问题ini_workState = myWork[--TOP];if (ini_workState.isPushed == 1) // 若当前状态是可行状态{ini_workState.s += w[ini_workState.n]; // 去掉当前状态的重量ini_workState.isPushed = 0;myWork[TOP++] = ini_workState;break;}}}}return isOK;}int main() {if ( knap(S0,N0) ) printf("此'背包问题'有解!/n");else printf("此'背包问题'无解!/n");return 0;}