07-图5 Saving James Bond

This time let us consider the situation in the movie "Live and Let Die" in which James Bond, the world's most famous spy, was captured by a group of drug dealers. He was sent to a small piece of land at the center of a lake filled with crocodiles. There he performed the most daring action to escape -- he jumped onto the head of the nearest crocodile! Before the animal realized what was happening, James jumped again onto the next big head... Finally he reached the bank before the last crocodile could bite him (actually the stunt man was caught by the big mouth and barely escaped with his extra thick boot).

Assume that the lake is a 100 by 100 square one. Assume that the center of the lake is at (0,0) and the northeast corner at (50,50). The central island is a disk centered at (0,0) with the diameter of 15. A number of crocodiles are in the lake at various positions. Given the coordinates of each crocodile and the distance that James could jump, you must tell him a shortest path to reach one of the banks. The length of a path is the number of jumps that James has to make.

Input Specification:

Each input file contains one test case. Each case starts with a line containing two positive integers N (≤100), the number of crocodiles, and D, the maximum distance that James could jump. Then N lines follow, each containing the (x,y) location of a crocodile. Note that no two crocodiles are staying at the same position.

Output Specification:

For each test case, if James can escape, output in one line the minimum number of jumps he must make. Then starting from the next line, output the position (x,y) of each crocodile on the path, each pair in one line, from the island to the bank. If it is impossible for James to escape that way, simply give him 0 as the number of jumps. If there are many shortest paths, just output the one with the minimum first jump, which is guaranteed to be unique.

Sample Input 1:

17 15
10 -21
10 21
-40 10
30 -50
20 40
35 10
0 -10
-25 22
40 -40
-30 30
-10 22
0 11
25 21
25 10
10 10
10 35
-30 10

Sample Output 1:

4
0 11
10 21
10 35

Sample Input 2:

4 13
-12 12
12 12
-12 -12
12 -12

Sample Output 2:

0


我的答案（最大N没过）

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>

#define QMAXSIZE 10000

struct Crocodile {
    int x;
    int y;
    int Visited;
    int Path;
};
typedef struct Crocodile *Point;

//队列部分
struct QNode {
    int Data[QMAXSIZE];
    int rear;
    int front;
};
typedef struct QNode *Queue;

int IsEmpty(Queue Q)
{
    return (Q->rear == Q->front);
}

void AddQ(Queue PtrQ, int item)
{
    if((PtrQ->rear+1)%QMAXSIZE == PtrQ->front) {
        printf("Queue full");
        return;
    }
    PtrQ->rear = (PtrQ->rear+1)%QMAXSIZE;
    PtrQ->Data[PtrQ->rear] = item;
}

int DeleteQ(Queue PtrQ)
{
    if(PtrQ->front == PtrQ->rear) {
        printf("Queue empty");
        return -1;
    } else {
        PtrQ->front = (PtrQ->front+1)%QMAXSIZE;
        return PtrQ->Data[PtrQ->front];
    }
}

void PrintQ(Queue PtrQ)
{
    int i;
    printf("[Queue]: ");
    for(i=(PtrQ->front+1)%QMAXSIZE;i!=(PtrQ->rear+1)%QMAXSIZE
            ;i=(i+1)%QMAXSIZE)
        printf("%d ", PtrQ->Data[i]);
    printf("
");
}//end Queue

void ReadPoint(Point P, int N)
{
    int i;
    P[0].x = 0;
    P[0].y = 0;
    P[0].Visited = 0;
    P[0].Path = -1;
    for(i=1;i<N;i++) {      //N=N+1
        scanf("%d %d
", &P[i].x, &P[i].y);
        P[i].Visited = 0;
    }
}

void PrintfPoint(Point P, int N)
{
    int i;
    for(i=0;i<N;i++) {      //N=N+1
        printf("P[%d] X:%d Y:%d
", i, P[i].x, P[i].y);
    }
    printf("----------------------------
");
}

void PrintPath(Point P, int stand)
{
    int Path[100], i;
    // printf("[PrintPath] stand=%d
", stand);
    // if(P[stand].Path != -1) {
    //     PrintPath(P, P[stand].Path);
    //     printf("%d %d
", P[stand].x, P[stand].y);
    // }   
    if(stand==0) printf("1
");
    else {
        for(i=0;P[stand].Path != -1;i++) {
            Path[i] = stand;
            stand = P[stand].Path;
        }   
        // printf("[PrintPaht] i=%d
", i);     
        printf("%d
", i+1);
        for(i--;i>=0;i--) {
            printf("%d %d
", P[Path[i]].x, P[Path[i]].y);
        }
    }
}

double PointDistance(Point P1, Point P2)
{
    return sqrt(pow((P1->x - P2->x), 2) + pow((P1->y - P2->y), 2));
}

double FindMinPath(Point P, int stand)
{
    while(P[stand].Path != 0) {
        stand = P[stand].Path;
    }
    return PointDistance(&P[0], &P[stand]);
}

int IsUp(Point P, int stand, double D, int island)
{
    int xlen = 50-abs(P[stand].x);
    int ylen = 50-abs(P[stand].y);
    if(island == 1 && (xlen<=(D+7.5) || ylen<=(D+7.5)))
        return 1;
    else if(stand!=1 && (xlen<=D || ylen <=D))
        return 1;
    return 0;
}

int IsUseless(Point P, int stand)
{
    if(abs(P[stand].x) <= 7.5 && abs(P[stand].y) <= 7.5 )
        return 1;
    else if(abs(P[stand].x == 50 && abs(P[stand].y == 50)))
        return 1;
    else 
        return 0;
}

void Visit(Point P, int stand)
{
    printf("[Point] P.x:%d y:%d
", P[stand].x, P[stand].y);
}

int BFS(Point P, int N, double D, int stand)
{
    Queue Q;
    int S, i, endP=-1;
    double dist, island = 0, minDist=100;

    Q = (Queue)malloc(sizeof(struct QNode)*N);
    // Visit(P, stand);                                //访问P[0]
    P[stand].Visited = 1;
    AddQ(Q, stand);

    while(!IsEmpty(Q)) {
        // PrintQ(Q);
        S = DeleteQ(Q);                             //提取队列
        if(S == 0)                                  //是否在岛上
            island = 1;
        else        
            island = 0;
        if(IsUp(P, S, D, island)) {
            endP = S;
            break;
        }

        for(i=1;i<N;i++) {
            if(IsUseless(P, i)) continue;
            dist = PointDistance(&P[S], &P[i]);
            if(!P[i].Visited && dist<=(D+(double)island*7.5)) {     //未被访问且能跳到
                // Visit(P, i);
                P[i].Path = S;
                if(IsUp(P, i, D, island)) {   
                    // printf("[Ok] Here Point can go up
");
                    // printf("[Path] 
");
                    // PrintPath(P, i);
                    // printf("
");
                    double temp;
                    temp = FindMinPath(P, i);
                    if(minDist > temp) {
                        minDist = temp;
                        endP = i;
                    }
                }
                P[i].Visited = 1;
                AddQ(Q, i);
                // dist = D+1;
            }
        }
    }
    return endP;
}

int main()
{
    int N, endP;
    double D;
    Point P;
    scanf("%d %lf", &N, &D);
    N++;        //从1开始
    P = (Point)malloc(sizeof(struct Crocodile)*N);
    ReadPoint(P, N);
    // PrintfPoint(P, N);

    endP = BFS(P, N, D, 0);
    // printf("minP:%d
", endP);
    if(endP == -1)
        printf("0
");
    else {
        PrintPath(P, endP);
    }
    return 0;
}