75 lines
2.3 KiB
C
75 lines
2.3 KiB
C
#include <bits/stdc++.h>
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struct heightpair {
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int height;
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int x;
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};
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void swap(struct heightpair *a, struct heightpair *b) {
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struct heightpair tmp = *a;
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*a = *b;
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*b = tmp;
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}
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void quicksort(struct heightpair *a, int le, int ri) {
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int i = le, j = ri - 1;
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struct heightpair pivot = a[(rand() %(ri - le)) + le];
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// printf("le = %d, ri = %d, pivot.height = %d\n", le, ri, pivot.height);
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// for (int i = le; i < ri; i++) {
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// printf("%d\n", a[i]);
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// }
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while (i <= j) {
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while (a[i].height > pivot.height) i++;
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while (a[j].height < pivot.height) j--;
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// printf("i = %d, j = %d\n", i, j);
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if (i <= j) swap(&a[i++], &a[j--]);
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}
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// for (int i = le; i < ri; i++) {
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// printf("%d\n", a[i]);
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// }
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// printf("----\n");
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if (le < j) quicksort(a, le, j + 1);
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if (i < ri - 1) quicksort(a, i, ri);
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}
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int maxArea(int *height, int heightSize) {
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struct heightpair *pairs = (struct heightpair *)malloc(heightSize * sizeof(struct heightpair));
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for (int i = 0; i < heightSize; i++) {
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pairs[i].height = height[i];
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pairs[i].x = i;
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}
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quicksort(pairs, 0, heightSize);
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// for (int i = 0; i < heightSize; i++) {
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// printf("%d, %d\n", pairs[i].height, pairs[i].x);
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// }
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struct heightpair curleft = pairs[0];
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struct heightpair curright = pairs[0];
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int curmax = 0;
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for (int i = 1; i < heightSize; i++) {
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if (pairs[i].x < curleft.x) {
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int vol = (curright.x - pairs[i].x) * pairs[i].height;
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curmax = curmax > vol ? curmax : vol;
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curleft = pairs[i];
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}
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else if (pairs[i].x < curright.x) {
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int vol1 = (pairs[i].x - curleft.x) * pairs[i].height;
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int vol2 = (curright.x - pairs[i].x) * pairs[i].height;
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curmax = curmax > vol1 ? curmax : vol1;
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curmax = curmax > vol2 ? curmax : vol2;
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} else {
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// pairs[i].x > curright.x
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int vol = (pairs[i].x - curleft.x) * pairs[i].height;
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curmax = curmax > vol ? curmax : vol;
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curright = pairs[i];
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}
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}
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return curmax;
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}
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int main() {
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int nums[] = {1,8,6,2,5,4,8,3,7};
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printf("%d\n", maxArea(nums, sizeof(nums) / sizeof(int)));
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return 0;
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} |