eno rate ask return red size all file 痛苦

Consider a town where all the streets are one-way and each street leads from one intersection to another. It is also known that starting from an intersection and walking through town‘s streets you can never reach the same intersection i.e. the town‘s streets form no cycles.

With these assumptions your task is to write a program that finds the minimum number of paratroopers that can descend on the town and visit all the intersections of this town in such a way that more than one paratrooper visits no intersection. Each paratrooper lands at an intersection and can visit other intersections following the town streets. There are no restrictions about the starting intersection for each paratrooper.

InputYour program should read sets of data. The first line of the input file contains the number of the data sets. Each data set specifies the structure of a town and has the format:

no_of_intersections
no_of_streets
S1 E1
S2 E2
......
Sno_of_streets Eno_of_streets

The first line of each data set contains a positive integer no_of_intersections (greater than 0 and less or equal to 120), which is the number of intersections in the town. The second line contains a positive integer no_of_streets, which is the number of streets in the town. The next no_of_streets lines, one for each street in the town, are randomly ordered and represent the town‘s streets. The line corresponding to street k (k <= no_of_streets) consists of two positive integers, separated by one blank: Sk (1 <= Sk <= no_of_intersections) - the number of the intersection that is the start of the street, and Ek (1 <= Ek <= no_of_intersections) - the number of the intersection that is the end of the street. Intersections are represented by integers from 1 to no_of_intersections.

There are no blank lines between consecutive sets of data. Input data are correct.
OutputThe result of the program is on standard output. For each input data set the program prints on a single line, starting from the beginning of the line, one integer: the minimum number of paratroopers required to visit all the intersections in the town.
Sample Input

2
4
3
3 4
1 3
2 3
3
3
1 3
1 2
2 3

Sample Output

2
1
題意：給你n個路口，m條街道，每行輸入路口a到路口b，傘兵只能沿著一條路走下去，沒有環形街道，問最少需要多少傘兵才能訪問所有路口。
思路：最小路徑覆蓋=頂點數-最大匹配數。
看到翻譯的時候我是崩潰的，作為我們隊的翻譯，我居然淪落到看別人翻譯的地步，立個flag，除非我把題目所有單詞
查完還不知道題意，否則絕對不百度翻譯，話說，二分圖建模好痛苦啊，我對這種題目一點想法都沒有，實在不行的話，以後這種題丟給隊友好了

#include<stdio.h>
#include<string.h>
#define
 
 N 500
int book[N],match[N],e[N][N];
int n,m;

int dfs(int u)
{
    int i;
    for(i = 1; i <= n; i ++)
    {
        if(!book[i]&&e[u][i])
        {
            book[i] = 1;
            if(!match[i]||dfs(match[i]))
            {
                match[i] = u;
                return 1;
            }
        }
    }
    
 
return 0;
}
int main()
{
    int i,t,j,sum,t1,t2;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        scanf("%d",&m);
        
        memset(e,0,sizeof(e));
        memset(match,0,sizeof(match));
        for(i = 1; i <= m; i ++)
        {
            scanf("%d%d",&t1,&t2);
            e[t1][t2] = 1;
        }
        sum = 0;
        for(i = 1; i <= n; i ++)
        {
            memset(book,0,sizeof(book));
            if(dfs(i))
                sum ++;
        }
        printf("%d\n",n-sum);
    }
    return 0;
}

【二分圖匹配入門專題1】E - Air Raid hdu1151【最小路徑覆蓋】