解题报告

题目传送门

题意：

有20个城市，只能征服相邻的城市，问要征服目的城市，最少需要征服多少城市（包括目的城市）

思路：

多源最短路，直接floyd，点才20个。

#include <iostream>
#include <cstring>
#include <cstdio>
#define inf 0x3f3f3f3f
using namespace std;
int mmap[100][100],n;
void floyd() {
    for(int k=1; k<=20; k++)
        for(int i=1; i<=20; i++)
            for(int j=1; j<=20; j++)
                if(mmap[i][j]>mmap[i][k]+mmap[k][j])
                    mmap[i][j]=mmap[i][k]+mmap[k][j];
}
int main() {
    int t,i,j,u,v,k=1,m;
    while(~scanf("%d",&m)) {
        for(i=1; i<=20; i++) {
            for(j=1; j<=20; j++)
                mmap[i][j]=inf;
            mmap[i][i]=0;
        }
        while(m--) {
            scanf("%d",&v);
            mmap[1][v]=mmap[v][1]=1;
        }
        for(i=2; i<=19; i++) {
            scanf("%d",&m);
            while(m--) {
                scanf("%d",&v);
                mmap[i][v]=mmap[v][i]=1;
            }
        }
        scanf("%d",&m);
        floyd();
        printf("Test Set #%d\n",k++);
        for(i=1; i<=m; i++) {
            scanf("%d%d",&u,&v);
            printf("%2d to %2d: %d\n",u,v,mmap[u][v]);
        }
        printf("\n");
    }
    return 0;
}

Risk

Risk is a board game in which several opposing players attempt to conquer the world. The gameboard consists of a world map broken up into hypothetical countries. During a player‘s turn, armies stationed in one country are only allowed to attack only countries with which they share a common border. Upon conquest of that country, the armies may move into the newly conquered country.

During the course of play, a player often engages in a sequence of conquests with the goal of transferring a large mass of armies from some starting country to a destination country. Typically, one chooses the intervening countries so as to minimize the total number of countries that need to be conquered. Given a description of the gameboard with 20 countries each with between 1 and 19 connections to other countries, your task is to write a function that takes a starting country and a destination country and computes the minimum number of countries that must be conquered to reach the destination. You do not need to output the sequence of countries, just the number of countries to be conquered including the destination. For example, if starting and destination countries are neighbors, then your program should return one.

The following connection diagram illustrates the first sample input.

Input 

There can be multiple test sets in the input file; your program should continue reading and processing until reaching the end of file. There will be at least one path between any two given countries in every country configuration.

Output 

The next N_T lines each will contain the result for the corresponding test in the test set - that is, the minimum number of countries to conquer. The test result line should contain the start country code A right-justified in columns 1 and 2; the string `` to " in columns 3 to 6; the destination country code B right-justified in columns 7 and 8; the string ``: " in columns 9 and 10; and a single integer indicating the minimum number of moves required to traverse from country A to country B in the test set left-justified starting in column 11. Following all result lines of each input set, your program should print a single blank line.

Sample Input 

1 3
2 3 4
3 4 5 6
1 6
1 7
2 12 13
1 8
2 9 10
1 11
1 11
2 12 17
1 14
2 14 15
2 15 16
1 16
1 19
2 18 19
1 20
1 20
5
1 20
2 9
19 5
18 19
16 20
4 2 3 5 6
1 4
3 4 10 5
5 10 11 12 19 18
2 6 7
2 7 8
2 9 10
1 9
1 10
2 11 14
3 12 13 14
3 18 17 13
4 14 15 16 17
0
0
0
2 18 20
1 19
1 20
6
1 20
8 20
15 16
11 4
7 13
2 16

Sample Output 

Test Set #1
 1 to 20: 7
 2 to  9: 5
19 to  5: 6
18 to 19: 2
16 to 20: 2

Test Set #2
 1 to 20: 4
 8 to 20: 5
15 to 16: 2
11 to  4: 1
 7 to 13: 3
 2 to 16: 4