[HDU 2732]Leapin' Lizards[拆点][SAP]

题目链接：[HDU 2732]Leapin' Lizards[拆点][SAP]

题意分析：

一张图，n行，m代表每行的长度，d代表蜥蜴每次能跳跃的最大距离。给出两张图，第一张图只含有0~3，代表蜥蜴能从上面经过的次数，第二张图代表蜥蜴的位置‘L'，'L’只存在于第一张图>0的区域。现在问：有多少蜥蜴留在了木桩上？

解题思路：

将木桩拆成两个点，中间连一条边，流量为第一张图的数值，然后每个距离<=d的木桩间连一条容量INF的边，最后s连蜥蜴，t连越界的木桩即可。注意输出！！！！

然后本题v最多400，加上拆点就800多个了，边的话也有很多，反正我用FF和Dinic都T了。。。。。然后就SAP横空出世了，好久没做网络流，这题被坑得好惨。

个人感受：

输出错了+网络流的点个数赋值错了，debug了一个晚上啊！！！！人家一个晚上刷完一个网络流专题，我特么就一道题！！！！

具体代码如下：

#include<algorithm>#include<cctype>#include<cmath>#include<cstdio>#include<cstring>#include<iomanip>#include<iostream>#include<map>#include<queue>#include<set>#include<sstream>#include<stack>#include<string>#define ll long long#define pr(x) cout << #x << " = " << (x) << '\n';using namespace std;const int MAXN = 1010;//点数的最大值const int MAXM = 540010;//边数的最大值const int INF = 0x3f3f3f3f;struct Edge{    int to,next,cap,flow;}edge[MAXM];//注意是MAXM//ans:蜥蜴个数 cnt:点的idint tol, n, k, ans, cnt, len, s, t;int id[30][30]; // 存点IDchar mp[30][30], liz[30][30];int head[MAXN];int gap[MAXN],dep[MAXN],cur[MAXN];void addedge(int u,int v,int w,int rw = 0){    edge[tol].to = v; edge[tol].cap = w; edge[tol].flow = 0;    edge[tol].next = head[u]; head[u] = tol++;    edge[tol].to = u; edge[tol].cap = rw; edge[tol].flow = 0;    edge[tol].next = head[v]; head[v] = tol++;}int Q[MAXN];void BFS(int start,int end){    memset(dep,-1,sizeof(dep));    memset(gap,0,sizeof(gap));    gap[0] = 1;    int front = 0, rear = 0;    dep[end] = 0;    Q[rear++] = end;    while(front != rear)    {        int u = Q[front++];        for(int i = head[u]; i != -1; i = edge[i].next)        {            int v = edge[i].to;            if(dep[v] != -1)continue;            Q[rear++] = v;            dep[v] = dep[u] + 1;            gap[dep[v]]++;        }    }}int S[MAXN];int sap(int start,int end,int N){    BFS(start,end);    memcpy(cur,head,sizeof(head));    int top = 0;    int u = start;    int ans = 0;    while(dep[start] < N)    {        if(u == end)        {            int Min = INF;            int inser;            for(int i = 0;i < top;i++)            if(Min > edge[S[i]].cap - edge[S[i]].flow)            {                Min = edge[S[i]].cap - edge[S[i]].flow;                inser = i;            }            for(int i = 0;i < top;i++)            {                edge[S[i]].flow += Min;                edge[S[i]^1].flow -= Min;            }            ans += Min;            top = inser;            u = edge[S[top]^1].to;            continue;        }        bool flag = false;        int v;        for(int i = cur[u]; i != -1; i = edge[i].next)        {            v = edge[i].to;            if(edge[i].cap - edge[i].flow && dep[v]+1 == dep[u])            {                flag = true;                cur[u] = i;                break;            }        }        if(flag)        {            S[top++] = cur[u];            u = v;            continue;        }        int Min = N;        for(int i = head[u]; i != -1; i = edge[i].next)            if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min)            {                Min = dep[edge[i].to];                cur[u] = i;            }        gap[dep[u]]--;        if(!gap[dep[u]]) return ans;        dep[u] = Min + 1;        gap[dep[u]]++;        if(u != start)u = edge[S[--top]^1].to;    }    return ans;}void init() {    scanf("%d%d", &n, &k);    tol = 0, ans = 0;    memset(head,-1,sizeof(head));    memset(id, 0, sizeof id);    for (int i = 0; i < n; ++i) scanf("%s", mp[i]);    for (int i = 0; i < n; ++i) scanf("%s", liz[i]);    cnt = 0, len = strlen(mp[0]);    for (int i = 0; i < n; ++i) {        for (int j = 0; j < len; ++j) if (mp[i][j] != '0') {            id[i][j] = ++cnt;        }    }}void make_map() {    for (int i = 0; i < n; ++i) {        for (int j = 0; j < len; ++j) {            if (id[i][j]) {                if (liz[i][j] == 'L') addedge(s, id[i][j], 1), ++ans;                addedge(id[i][j], id[i][j] + cnt, mp[i][j] - '0');                for (int a = -k; a <= k; ++a)                for (int b = -k; b <= k; ++b) {                    int judge = abs(a) + abs(b);                    if (judge != 0 && judge <= k) {                        int x = i + a, y = j + b;                        if (0 <= x && x < n && 0 <= y && y < len) {                            addedge(id[i][j] + cnt, id[x][y], INF);                        }                        else addedge(id[i][j] + cnt, t, INF);                    }                }            }        }    }}int main(){    #ifdef LOCAL    freopen("C:\\Users\\apple\\Desktop\\in.txt", "r", stdin);    #endif    for (int kk, kase = scanf("%d", &kk); kase <= kk; ++kase) {        init();        s = 0, t = cnt * 2 + 1;        make_map();        ans -= sap(s, t, cnt * 2 + 2);        if (ans > 1)            printf("Case #%d: %d lizards were left behind.\n", kase, ans);        else if (ans == 1)            printf("Case #%d: %d lizard was left behind.\n", kase, ans);        else printf("Case #%d: no lizard was left behind.\n", kase);    }    return 0;}