アルゴリズムノート練習問題解合集
タイトルリンク

タイトル

タイトルはLong time ago,Kitty lived in a small village.The air was fresh and the scenery was very beautiful. The only thing that troubled her is the typhoon. When the typhoon came, everything is terrible. It kept blowing and raining for a long time. And what made the situation worse was that all of Kitty’s walls were made of wood. One day, Kitty found that there was a crack in the wall. The shape of the crack is a rectangle with the size of 1×L (in inch). ラッキー・キティゴートN blocks and a saw(ノコギリ)from her neighbors.The shape of the blocks were rectangle too, and the width of all blocks were 1 inch. So, with the help of saw, Kitty could cut down some of the blocks(of course she could use it directly without cutting) and put them in the crack, and the wall may be repaired perfectly, without any gap. Now, Kitty knew the size of each blocks, and wanted to use as fewer as possible of the blocks to repair the wall, could you help her?
The problem contains many test cases,please process to the end of file(EOF)を入力.Each test case contains two lines. In the first line, there are two integers L(0 In the second line, there are N positive integers. The ith integer Ai(0
出力For each test case,print an integer which represents the minimal number of blocks are needed.If Kitty could not repair the wall, just print “impossible” instead.
サンプル入力

2 2
12 11 
14 3
27 11 4 
109 5
38 15 6 21 32 
5 3
1 1 1

サンプル出力

1
1
5
impossible

構想

すべてのblockを長さ順に並べて、長いものから使い始め、最後に補完できるように出力して何枚か使って、全部使っても補完できないようにimpossibleを出力します.

コード#コード#

#include 
#include 
int cmpInt(const void *ca, const void *cb){
	return *(int*)ca < *(int*)cb;
} 
int main(){
	int L, N, i;
	while (scanf("%d", &L) != EOF){
		scanf("%d", &N);
		int ans = 0;	//        
		int blocks[N]; 
		for (i = 0; i < N; ++i)
			scanf("%d", &blocks[i]);
		qsort(blocks, N, sizeof(int), cmpInt);
		i = 0;
		while(L > 0 && i < N){
			L -= blocks[i++];
			++ans;
		} 
		if (L <= 0){
			printf("%d
", ans); 
		} else {
			printf("impossible
"); 
		} 
	} 
	return 0;
}