int bi_search(int numbers[], int b_n, int e_n, int val) {
if (b_n > e_n)
return 0;
int mid = (b_n + e_n) / 2;
if (numbers[mid] == val) {
return 1;
}
// 这里二分查找明显不是最优，因为numbers已经排好序，所以下面只需要查找一侧即可
if (bi_search(numbers, b_n, mid-1, val) || bi_search(numbers, mid+1, e_n, val)) {
return 1;
}
return 0;
}
int bi_search(vector<int>& v, int i, int j, int target) {
int mid = (i+j)/2;
if (i>j && i>=v.size()) // right out
return 2;
else if (i>j && j<0) // left out
return -1;
else if (i > j) // not found
return 0;
if (v[mid] == target)
return 1;
else if (v[mid] < target)
return bi_search(v, mid+1, j, target);
else if (v[mid] > target)
return bi_search(v, i, mid-1, target);
// return 1 found, -1 less, 2 biger, 0 not found
}
int main()
{
SeqList sl;
int i, j, k, t;
printf("input the elements in escendant order:\n");
i = 0;
scanf("%d", &(sl.data[i]));
while(i < N-1){
scanf("%d", &t);
if(t > sl.data[i]){
i++;
sl.data[i] = t;
}else{
printf("error, must bigger than %d\n", sl.data[i]);
}
}
sl.length = N;
printf("input the key:\n");
scanf("%d", &k);
j = bi_search(&sl, k);
printf("-------------------\n");
if(j >= 0){
printf("found : data[%d]\n", j);
}else{
printf("%d is not been found\n", k);
}
return 0;
}
int bi_delete(int key, int a[], int *np)
{
int p;
int i;
if (*np > 0)
{
if ((p = bi_search(key, a, *np)) < 0) return -1;
for (i = p+1; i < *np; i++) a[i-1] = a[i];
(*np)--;
return p;
}
return -1;
}
void li_test(int a[], int n)
{
int i;
long t1, t2;
t1 = get_tick();
for (i = 0; i < LOOP; i++) bi_search(random(30000), a, n);
t2 = get_tick();
printf("\n li_search %d loops ellapse %ld ticks.", LOOP, diff_tick(t1,t2));
t1 = get_tick();
for (i = 0; i < LOOP; i++) bii_search(random(30000), a, n);
t2 = get_tick();
printf("\n lfi_search %d loops ellapse %ld ticks.", LOOP, diff_tick(t1,t2));
}
bool searchMatrix(vector<vector<int>>& matrix, int target) {
if (matrix.empty()) return false;
int n = matrix[0].size();
int i = 0;
int j = matrix.size() -1;
while (i <= j) {
int mid = (i+j)/2;
int flag = bi_search(matrix[mid], 0, n, target);
if (flag == 1) return true;
if (flag == 0) return false;
if (flag == -1) j = mid-1;
if (flag == 2) i = mid+1;
}
return false;
}
void interpret(int a[], int *np, int N)
{
char command[2];
char key[2];
int p;
while (command[0] != 'q')
{
printf("\nInput command ->");
scanf("%1s", command);
scanf("%1s", &key);
switch (command[0])
{
case 'i' :
case 'I' : if (*np < N)
{
bi_insert(key[0], a, np);
printf("\n Successful insert.");
}
else
printf("\n Error : Table full.");
break;
case 'd' :
case 'D' : if (bi_delete(key[0], a, np) < 0)
printf("\n Error : Table Empty.");
else
printf("\n Successful delete.");
break;
case 's' :
case 'S' : if ((p = bi_search(key[0], a, *np)) < 0)
printf("\n Error : Can'f find that key");
else
printf("\n Ok! find in %d th position", p);
break;
case 'f' :
case 'F' : if ((p = bii_search(key[0], a, *np)) < 0)
printf("\n Error : Can't find that key");
else
printf("\n Ok ! find in %d th position & move front", p);
break;
case 'l' :
case 'L' : bi_list(a, *np);
break;
}
printf(" n = %d", *np);
}
}
int *twoSum(int numbers[], int n, int target) {
int i = 0, j = n -1, k, sub_val;
int ans[2];
int *tmp = (int *)malloc(n * sizeof(int));
memcpy(tmp, numbers, n * sizeof(int));
qsort((void *)numbers, n, sizeof(int), compare);
if(false) {
//通过二分查找确定
for (i = 0; i < n; ++i) {
sub_val = target - numbers[i];
if (bi_search(numbers, i+1, n-1, sub_val)) {
break;
}
}
} else {
//通过两端遍历查找确定
while(i < j) {
if(numbers[i] + numbers[j] == target) {
sub_val = numbers[j];
break;
} else if(numbers[i] + numbers[j] < target) {
i++;
} else {
j--;
}
}
}
for (j = 0; j < n; ++j) {
if(tmp[j] == numbers[i] || tmp[j] == sub_val) {
ans[0] = j+1;
break;
}
}
for (j++; j < n; ++j) {
if(tmp[j] == numbers[i] || tmp[j] == sub_val) {
ans[1] = j+1;
break;
}
}
return ans;
}
