foo hit contest 每次 int total program target friend

題目鏈接：http://acm.hdu.edu.cn/showproblem.php?pid=3038

解題思路：首先，由於序列數據可正可負，因此實際不滿足情況的只有已知區間樣例中所給出的那種情況類似。所以，使用並查集判斷區間是否連通，使用前綴和來計算是否滿足條件即可。

使用帶權並查集，val數組記錄前綴和，對於[a, b]，fa = find(a), fb = find(b)，合並的時候val[fb]只表示[fa, fb]的距離，而在每次find的時候才完成了 val值轉換為前綴和+路徑壓縮。

如果區間兩個端點不連通，說明他們的值未知，合並，更新val

如果區間兩個端點連通，那麽通過前綴和（已經在find同時算出）判斷是否與題目中描述相同。

註意多組數據！

代碼：

 1 const int inf = 0x3f3f3f3f;
 2 const int maxn = 200010;
 3 int fa[maxn], val[maxn], n, m;
 4 
 5 int find(int x){
 6     if(x == fa[x]) return x;
 7     int tmp = find(fa[x]);
 8     val[x] += val[fa[x]];
 9     fa[x] = tmp;
10     return tmp;
11 }
12 int main(){
13     while(scanf("%d %d
 
", &n, &m) != EOF){
14         for(int i = 0; i <= n; i++){
15             fa[i] = i;
16             val[i] = 0;
17         }
18         int ans = 0;
19         while(m--){
20             int a, b, x;
21             scanf("%d %d %d", &a, &b, &x);
22             a -= 1;
23             int
 
 ra = find(a);
24             int rb = find(b);
25             if(ra != rb){
26                 fa[rb] = ra;
27                 val[rb] = val[a] + x - val[b]; 
28             }
29             else{
30                 if(val[b] - val[a] != x) ans++;
31             }
32         }
33         printf("%d\n", ans);
34     }
35 }

題目：

How Many Answers Are Wrong

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 9297 Accepted Submission(s): 3377

Problem Description TT and FF are ... friends. Uh... very very good friends -________-b

FF is a bad boy, he is always wooing TT to play the following game with him. This is a very humdrum game. To begin with, TT should write down a sequence of integers-_-!!(bored).

Then, FF can choose a continuous subsequence from it(for example the subsequence from the third to the fifth integer inclusively). After that, FF will ask TT what the sum of the subsequence he chose is. The next, TT will answer FF‘s question. Then, FF can redo this process. In the end, FF must work out the entire sequence of integers.

Boring~~Boring~~a very very boring game!!! TT doesn‘t want to play with FF at all. To punish FF, she often tells FF the wrong answers on purpose.

The bad boy is not a fool man. FF detects some answers are incompatible. Of course, these contradictions make it difficult to calculate the sequence.

However, TT is a nice and lovely girl. She doesn‘t have the heart to be hard on FF. To save time, she guarantees that the answers are all right if there is no logical mistakes indeed.

What‘s more, if FF finds an answer to be wrong, he will ignore it when judging next answers.

But there will be so many questions that poor FF can‘t make sure whether the current answer is right or wrong in a moment. So he decides to write a program to help him with this matter. The program will receive a series of questions from FF together with the answers FF has received from TT. The aim of this program is to find how many answers are wrong. Only by ignoring the wrong answers can FF work out the entire sequence of integers. Poor FF has no time to do this job. And now he is asking for your help~(Why asking trouble for himself~~Bad boy)

Input Line 1: Two integers, N and M (1 <= N <= 200000, 1 <= M <= 40000). Means TT wrote N integers and FF asked her M questions.

Line 2..M+1: Line i+1 contains three integer: Ai, Bi and Si. Means TT answered FF that the sum from Ai to Bi is Si. It‘s guaranteed that 0 < Ai <= Bi <= N.

You can assume that any sum of subsequence is fit in 32-bit integer.

Output A single line with a integer denotes how many answers are wrong.

Sample Input 10 5 1 10 100 7 10 28 1 3 32 4 6 41 6 6 1

Sample Output 1

Source 2009 Multi-University Training Contest 13 - Host by HIT

HDU 3038 How Many Answers Are Wrong