POJ1062 昂贵的聘礼 【DFS】[通俗易懂]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define maxn 110
#define inf 0x3f3f3f3f

struct Node {
    int price, level, down;
} G[maxn];
int head[maxn], m, n, id;
struct Node2 {
    int v, val, next;
} E[maxn * maxn];
bool vis[maxn];
int sta[maxn], id2; // sta防止间接等级越界

void addEdge(int u, int v, int val) {
    E[id].v = v; E[id].next = head[u];
    E[id].val = val; head[u] = id++;
}

int min(int a, int b) {
    return a < b ? a : b;
}

int DFS(int u) {
    for(int i = 0; i < id2; ++i)
        if(abs(sta[i] - G[u].level) > m) 
            return inf;
    int v, ans = G[u].price;
    for(int i = head[u]; i != -1; i = E[i].next) {
        if(vis[v = E[i].v]) return inf;
        vis[v] = 1; sta[id2++] = G[u].level;
        ans = min(ans, E[i].val + DFS(v));
        vis[v] = 0; --id2;
    }
    return ans;
}

int solve() {
    memset(vis, 0, sizeof(bool) * (n + 1));
    int i, j, v, ans = G[1].price; vis[1] = 1;
    id2 = 0; sta[id2++] = G[1].level;
    for(i = head[1]; i != -1; i = E[i].next) {
        v = E[i].v; 
        ans = min(ans, E[i].val + DFS(v));
    }
    return ans;
}

int main() {
    int i, j, v, val;
    while(scanf("%d%d", &m, &n) == 2) {
        memset(head, -1, (n + 1) * sizeof(int));
        for(i = 1, id = 0; i <= n; ++i) {
            scanf("%d%d%d", &G[i].price, &G[i].level, &G[i].down);
            for(j = 0; j < G[i].down; ++j) {
                scanf("%d%d", &v, &val);
                addEdge(i, v, val);
            }
        }
        printf("%d\n", solve());
    }
    return 0;
}

2015.2.7更新

#include <stdio.h>
#include <string.h>

#define inf 0x3f3f3f3f
#define maxn 110

struct Node {
	int P, L, X; // 价格、主人等级、替代品数
} goods[maxn];
struct Node2 {
	int T, V; // 编号、价格优惠
} substi[maxn][maxn];
int M, N;
bool vis[maxn];

int min(int a, int b) { return a < b ?
 a : b; }int max(int a, int b) { return a > b ? a : b; }int solve(int numOfGoods, int minLevel, int maxLevel) {	if (maxLevel - minLevel > M) return inf;	int tempNumOfGoods, minL, maxL, i;	int result = goods[numOfGoods].P;	for (i = 1; i <= goods[numOfGoods].X; ++i) {		tempNumOfGoods = substi[numOfGoods][i].T;		if (vis[tempNumOfGoods]) continue;		vis[tempNumOfGoods] = true;		minL = min(minLevel, goods[tempNumOfGoods].L);		maxL = max(maxLevel, goods[tempNumOfGoods].L);		result = min(result, solve(tempNumOfGoods, minL, maxL) + substi[numOfGoods][i].V);		vis[tempNumOfGoods] = false;	}	return result;}int main() {	// freopen("data.in", "r", stdin);	int i, j;	while (scanf("%d%d", &M, &N) == 2) {		memset(vis, 0, sizeof(vis));		for (i = 1; i <= N; ++i) {			scanf("%d%d%d", &goods[i].P, &goods[i].L, &goods[i].X);			for (j = 1; j <= goods[i].X; ++j)				scanf("%d%d", &substi[i][j].T, &substi[i][j].V);		}		printf("%d\n", solve(1, goods[1].L, goods[1].L));	}	return 0;}

2015.04.13更新

#include <stdio.h>
#include <string.h>

const int maxn = 110;
const int inf = 0x3f3f3f3f;
int head[maxn], id;
struct Node {
    int v, w, next;
} E[maxn*maxn];
struct Node2 {
    int price, level;
} Per[maxn];
int N, M, dp[maxn];   // N articles

int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }

void addEdge(int u, int v, int w)
{
    E[id].v = v;
    E[id].w = w;
    E[id].next = head[u];
    head[u] = id++;
}

void getMap()
{
    int i, j, P, L, K, w, v;

    memset(head, -1, sizeof(head));
    memset(dp, 0, sizeof(dp));

    for (id = 0, i = 1; i <= N; ++i) {
        scanf("%d%d%d", &P, &L, &K);
        Per[i].price = P;
        Per[i].level = L;
        while (K--) {
            scanf("%d%d", &v, &w);
            addEdge(i, v, w);
        }
    }
}

int findMinCost(int k, int maxLevel, int minLevel)
{
    maxLevel = max(maxLevel, Per[k].level);
    minLevel = min(minLevel, Per[k].level);
    if (maxLevel - minLevel > M)
        return inf;
    else if (dp[k]) return dp[k];

    int ret = Per[k].price;
    int i, v;

    dp[k] = Per[k].price;
    for (i = head[k]; i != -1; i = E[i].next) {
        v = E[i].v;
        dp[k] = min(dp[k], findMinCost(v, maxLevel, minLevel) + E[i].w);
    }

    return dp[k];
}

int solve()
{
    return findMinCost(1, Per[1].level, Per[1].level);
}

int main()
{
    while (~scanf("%d%d", &M, &N)) {
        getMap();
        printf("%d\n", solve());
    }
    return 0;
}