LeetCode 第 31 场双周赛
作者:互联网
1 int countOdds(int low, int high){ 2 int ans = (high - low) / 2 + 1; 3 if ((low % 2 == 0 ) && (high % 2 == 0)) ans--; 4 return ans; 5 }View Code
arr前缀和,记录前缀和为奇数的地方,再搞个前缀和。
1 int numOfSubarrays(int* arr, int arrSize){ 2 int mod = 1e9 + 7; 3 int sum[arrSize + 10], odd[arrSize + 10]; 4 int ans = 0; 5 sum[0] = arr[0]; 6 if (arr[0] % 2) odd[0] = 1, ans++; 7 else odd[0] = 0; 8 for (int i = 1; i < arrSize; i++) { 9 sum[i] = sum[i - 1] + arr[i]; 10 odd[i] = odd[i - 1]; 11 if(sum[i] % 2) odd[i]++, ans++; 12 } 13 for (int i = 1; i < arrSize; i++) { 14 if (sum[i - 1] % 2) { 15 int evencnt = (arrSize - i) - (odd[arrSize - 1] - odd[i - 1]); 16 ans = (ans + evencnt ) % mod; 17 } else{ 18 int oddcnt = (odd[arrSize - 1] - odd[i - 1]); 19 ans = (ans + oddcnt ) % mod; 20 } 21 } 22 return ans; 23 }View Code
1 int numSplits(char * s){ 2 int n = strlen(s); 3 int a[n + 10][30]; 4 for (int i = 0; i < 26; i++) a[0][i] = 0; 5 a[0][s[0] - 'a']++; 6 for (int i = 1; i < n; i++) { 7 for (int j = 0; j < 26; j++) a[i][j] = a[i - 1][j]; 8 a[i][s[i] - 'a']++; 9 } 10 int ans = 0; 11 for (int i = 0; i < n; i++) { 12 int l = 0, r = 0; 13 for (int j = 0; j < 26; j++) { 14 if (a[i][j] > 0) l++; 15 if ((a[n - 1][j] - a[i][j]) > 0) r++; 16 } 17 if (l == r) ans++; 18 } 19 return ans; 20 }View Code
只需要考虑升序,把升序相邻之间的差值处理下。降序的数字增加可以通过延长升序范围处理掉。
1 int minNumberOperations(int* target, int targetSize){ 2 int res = target[0]; 3 for (int i = 1; i < targetSize; i++) { 4 if (target[i] > target[i - 1]) res += (target[i] - target[i - 1]); 5 } 6 return res; 7 }View Code
标签:arrSize,int,31,双周,sum,++,ans,odd,LeetCode 来源: https://www.cnblogs.com/ehanla/p/13881987.html