POJ 2075

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POJ2075是到PRIM练习题，但是很坑爹。有个很奇怪的问题就是：输出浮点数%.1f就过 %.1lf就不过。如果有人知道原因，请一定告知！不知道是不是.1f是四舍五入的 %.1lf是取floor的？

#include <cstdio>#include <cstring>#include <climits>using std::memset;const int MAX = 1005;double totallength;double map[MAX][MAX];char house[MAX][30];int n,m;double prim(){    bool visit[MAX];    double dis[MAX];    memset(visit, 0, sizeof(visit));    for(int i = 0 ; i < n; i++)    dis[i] = -1;    dis[0] = 0;    double ans = 0;    for(int i = 0 ; i< n; i++)    {        //find mingap        double mindis = INT_MAX;int minindex = -1;        for(int j = 0 ; j < n; j++)        {            if(!visit[j] && dis[j]!= -1 && mindis > dis[j])            {                mindis = dis[j];                minindex = j;            }        }        visit[minindex] = 1;        ans += mindis;        int from = minindex;        for(int to = 0 ; to < n; to++)        {            if(visit[to])            continue;            if(map[from][to] == 0)            continue;            if(dis[to] == -1 || map[from][to] < dis[to])            {                dis[to] = map[from][to];            }        }    }    return ans;}int main(){    while(scanf("%lf", &totallength)!=EOF)    {        scanf("%d", &n);        for(int i = 0 ; i< n; i++)        scanf("%s", house[i]);        scanf("%d", &m);        for(int i = 0 ; i < m; i++)        {            char house1[30], house2[30];            double length;            scanf("%s %s %lf", &house1, &house2, &length);            int house1index, house2index;            for(int j = 0 ; j < n; j++)            {                if(strcmp(house1, house[j]) == 0)                house1index = j;            }            for(int j = 0 ; j < n; j++)            {                if(strcmp(house2, house[j]) == 0)                house2index = j;            }            map[house1index][house2index] = length;            map[house2index][house1index] = length;        }        double ans = prim();        if(ans > totallength)        printf("Not enough cable\n");        else        printf("Need %.1f miles of cable\n", ans);    }}